Can you please do a screencast about the issue happening, so we could understand the exact location where the error is happening.

Thanks

We are checking the matter from agency account if there any issue.

We have given an update by some tweaking. Please check now if it's working now.

Thanks

After checking on a client end, we found that, you are trying to connect account from other account who is not admin of the APP before getting advance access of 'Catalog Management', 'WhatsApp Business Management', 'WhatsApp Business Messaging'. So before getting access for all other people your Facebook APP must need to get approval for this 3 permissions.

Thanks