"You do not have a valid PowerApps Plan" - We have workaround but hard for end users

[MSAdmin]

I built a canvas app for my company (company1) that uses a separate SharePoint Online domain company2.sharepoint.com. This app is hosted in a separate domain from my company, and we all use guest invitations to access this website and powerapp. We all get this error. We then go to powerapps.microsoft.com and log in to powerapps with our company1 account, then come back to company2.sharepoint.com and the error goes away. I really don't want to train 200 people to perform this workaround, any way for this error to go away?

[MSAdmin]

[Pstork1]

Is there some reason it needs to be in a different tenant?  

[MSAdmin]

Hi Paul - We can re-examine our architecture if necessary but is this scenario supported? Part of the reason is that we can casually invite B2B users into this other tenant to collaborate, inviting B2B users into our main tenant involves a lot of governance and CM.

[Pstork1]

I understand the reason, and it is essentially valid.  The problem is that in that second tenant all your users are essentially guest users in the tenant.  But unlike SharePoint guest users Power Apps guest users must have a valid license, either in the guest tenant or in their home tenant.  So you can use the licenses you already have, but that requires that users sign in to the home tenant so that the license is recognized by the guest tenant.  If the app doesn't use any premium connectors and if the users have O365 licenses in both tenants you should be able to assign the guests a license in the second tenant and then they wouldn't have to login to the home tenant.  But that is dependent on having double the licenses.

[MSAdmin]

so pretend my company wants to host a public event and asks me to build an event registration page, and I use powerapps, and thousands of people with their O365 accounts receive this error, and MS says "nothing wrong here"? Is PowerApps not meant for B2B scenarios?

[Pstork1]

Power Apps can be used in a B2B scenario, but that doesn't remove the requirement that users have to be licensed either in their home tenant or the guest tenant. For Office 365 B2B all the guest users need to be added to Your tenant's Azure AD.  For Power Apps they also need a valid license.

For the scenario you describe I would probably be looking at a Power Apps Portal app, which can be done anonymous access and is licensed by the page hit rather than user license.

Take a look at this guide https://powerapps.microsoft.com/en-us/blog/share-canvas-apps-with-guests-in-your-organization/

[MSAdmin]

"Power Apps can be used in a B2B scenario, but that doesn't remove the requirement that users have to be licensed either in their home tenant"

All my users are licensed in their home tenant, we're O365 E3, and they are all getting licensing errors the guest tenant.

[Pstork1]

And their licenses work from the home tenant, but that's why they have to be logged into the home tenant to use their license from there.  Otherwise the guest tenant doesn't know that they have a license elsewhere.  So the behavior you described in your original post is the expected behavior.  If they are going to rely on the license in their home tenant then they need to be logged in to their home tenant.