Can some please help me figure out the issue I am having with WHMCS Provisioning

I am having an issue with accepting an order. I get this error message I am not able to figure out:
Order Accept Encountered Problems Is not a valid domain name, alphanumeric and "-" only:

WHMCS support reviewed it and responded in this way:
Hello Nigel

I've reviewed your WHMCS installation and everything appears to be setup correctly. Since you are using a 3rd party module for provisioning your WP-MultiSites you will need to get in contact with them for information on that specific error message.

Let us know if you have any further questions or issues!

The login detail is in the dropbox. Jack should have access to that and at least two other team members.