Are they a prior client and have passed KBA before?

First year client

If the client can't pass the KBA, the client will need to sign it some other way.

They may need to print out the physical paper form, sign it, and return it to you (either by scanning and uploading or by mailing/dropping it off).

Can you please explain the process of that? Or is there any video that shows the steps? Thank you

In that case, yeah you need KBA or gotta print it to a PDF and have the client do a wet signature, scan, and send it back to you.