Hi Nam,
By our records, you are working with GD Cloud and not with a GD Platform product.
No worries about that, but rather post your future inquiries to the
#gooddata-cloud channel, so it reaches the right audience.
I am think I know what is the issue here. In you Trial, you were using the Invite button in your UI, correct? This function is tied to the GD managed OpenID Connect Identity Provider, which is used for authentication of invited users.
However, when you switch to the Professional/Enterprise tier, your organization is ready for implementation of your own OIDC(more details can be found
here).
Part of the onboarding email with instructions was also this paragrapg:
We assume that you will be using your own OIDC in the future. Once you are ready to switch from our OIDC to your own, please follow these steps. Due to this planned transition, the invitation functionality is not available anymore, as it was linked to our OIDC. You can add new users once you switch to your own OIDC.
If you need any users added to help with implementing your OIDC, please let us know, and we will gladly assist.