My client cannot get verification code in order to start new account.

My client has a large business and has created a new email for a conference room computer they have put together. It is a Microsoft 365 Business Standard licensed account. I am their IT consultant and Microsoft 365 Global Admin and have whitelisted all IPs, senders and domains per Zoom KB, but we cannot get the code. I have heard of other people experiencing this and Zoom support found various causes. What can I do? oh yeah, we have definitely checked spam/junk and potential rules. Thank you so much in advance!