Publish Application Group to external users

Hi,

I am trying to publish an application to external people which are invited to AAD as guest user.  The application is published through an Application Groupn in a Host Pool.

These guest users have sometimes gmail, hotmail accounts.

Why is the application not visible for these users? Do they need a license? If so, which one? And are Hotmail and Gmail accounts allowed?

I hope someone is willing to help me.

Thanks in advance

Best Regards

Raymond