Hi @cstevens44 


You have to differentiate "guest users" vs "Teams external users": 

- "Guest users" are users known from Azure AD B2B with whom you can collaborate (e.g. within a Teams) or share content (e.g. within SharePoint)

-  "External users" are users with whom you communicate through Teams (1:1 or 1:N chat or meeting). They are not registered in your Azure AD


The prerequisite for external users is to authorize the federation between your tenant and the tenant of your external users. By default, this setting (Teams Admin Center > Users > External Access) is set to "allow external domains". What is the status in your organization? 


If you want to enable non authenticated users, you can activate the feature "Anonymous users can join a meeting".  


Hope this helps!