Hi
A tiny bit bigger
I was waiting for the answer from the OP about whether there are other digits.
Assuming there may be other digits in the string (groups less than 8) I tried this:
=IFERROR(MID(A1,SMALL(IF(MMULT(0+ISERROR(-MID($A1,ROW(INDIRECT("1:"&LEN(A1)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A1)-7))),
1),8),"")
&IFERROR("/"&MID(A1,SMALL(IF(MMULT(0+ISERROR(-MID($A1,ROW(INDIRECT("1:"&LEN(A1)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A1)-7))),
2),8),"")
I left a "/" between the 2 groups for testing purposes.
Although a bit big it's easy to expand. The second line is the same as the first one, just replace the 1 with 2. If we had for ex. up to 4 groups you'd just add more rows:
=IFERROR(MID(A4,SMALL(IF(MMULT(0+ISERROR(-MID($A4,ROW(INDIRECT("1:"&LEN(A4)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A4)-7))),
1),8),"")
&IFERROR("/"&MID(A4,SMALL(IF(MMULT(0+ISERROR(-MID($A4,ROW(INDIRECT("1:"&LEN(A4)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A4)-7))),
2),8),"")
&IFERROR("/"&MID(A4,SMALL(IF(MMULT(0+ISERROR(-MID($A4,ROW(INDIRECT("1:"&LEN(A4)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A4)-7))),
3),8),"")
&IFERROR("/"&MID(A4,SMALL(IF(MMULT(0+ISERROR(-MID($A4,ROW(INDIRECT("1:"&LEN(A4)-7))+{0,1,2,3,4,5,6,7},1)),{1;1;1;1;1;1;1;1})=0,ROW(INDIRECT("1:"&LEN(A4)-7))),
4),8),"")
which makes easy to adapt to the needs.
In this test in rows 2 and 4 I added other digits in the string that are ignored.
<table border="1" cellpadding="1" style="background:#FFF; border-collapse:collapse;border-width:2px;border-color:#CCCCCC;font-family:Arial,Arial; font-size:10pt" ><tr><th style="border-width:1px;border-color:#888888;background:#9CF " > </th><th style="border-width:1px;border-color:#888888;background:#9CF; text-align:center" >A</th><th style="border-width:1px;border-color:#888888;background:#9CF; text-align:center" >B</th><th style="border-width:1px;border-color:#888888;background:#9CF; text-align:center" width=30 >C</th></tr><tr><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;background:#9CF; text-align:center; " ><b>1</b></td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">AB 90197611</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">90197611</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td></tr><tr><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;background:#9CF; text-align:center; " ><b>2</b></td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">1A94235127B23C/66932742/</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">94235127/66932742</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td></tr><tr><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;background:#9CF; text-align:center; " ><b>3</b></td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; "> </td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td></tr><tr><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;background:#9CF; text-align:center; " ><b>4</b></td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">A94235127AB/66932742/C1D23E456F93100051/<br>G61088053</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; ">94235127/66932742/93100051/61088053</td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td></tr><tr><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;background:#9CF; text-align:center; " ><b>5</b></td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:left;border-width: 1px;border-color:#888888; "> </td><td style="border-width:1px;border-color:#000000; padding-left:0.5em; padding-top:0.4em; padding-right:0.5em; padding-bottom:0.25em;text-align:right;border-width: 1px;border-color:#888888; "> </td></tr><tr><td colspan=4 style="background:#9CF; padding-left:1em" > [Book1]Sheet2</td></tr></table>