I've taken a test user from my tenant, added subscription Licensing for both D365 & Office 356 E5; and permissioned them to use Remote Assist. I've downloaded the app from the link that was emailed to the user. When I open the app and choose to login with the user's AAD credentials (the same AAD credential used to log into the HoloLens, and in the Office Admin Portal); I receive "Subscription Needed: Make sure you are using a work or school account with an active subscription for Remote Assist."
I have added this user to the subscription; they received the email invite and install link for the product. The only account used on the HoloLens since it was reset is the same AAD user that was permissioned.
Ideas?