Help with Licenses for external users in M365 EDU

Posted this before and  now not seeing it, so apologies for any duplicate;

I have a EDU tenant.

Most of our faculty are adjunct and prefer to use their own emails (these are not work/school accounts).

I have:
1. Added as a guest user via invitation. then can redeem invite, but are unable to log in.

2. converted to member in AAD

3. Assigned a faculty A3 license.

4. They are able to log in to portal.azure.com. They are able to log in to the sharepoint.
5. however, when i send a link to download apps associated with their licenses, it never arrives. 

6. If they select "apps" or "office" from the launcher menu, and attempt to sign in, they get a "You can't sign in here with a personal account" message.
I am confused- if I can add them and assign a license, why can they not get the benefits of that license. Is this a restriction with EDU tenants?