I only see two options, assuming you are keeping the client:

1.  Print out return and substitute clients Forms 8949 with those generated by program after you make one total entry each for each type of 8949 transaction (Box A, Box B, etc),  and mail in return; OR

2.  Have client provide you instead of the Forms 8949 the Excel spreadsheets which the crypto company also provided him.  Put those into a pdf and attach to return.  Take the totals for each type of Form 8949 transaction (Box A, Box B, etc) and enter on 1099B Worksheet by type something like this in the description area "XYZ Co. Crypto Transactions - See Detail Attached".  Those total will then print on Forms 8949.

Option 2 is the way to proceed.