Unlike for a default environment for a new trial environment, your Office 365 users won’t get the access automatically and you can’t manage this access via Microsoft Office 365 Admin portal. Or even via model-driven UI for your newly set up environment. You have to add users one by one using the steps below.
Click on the environment you would like to set up users on. Go to the Security tab.
Type user login for Step 1 to add a user. Click Add User.
As a result, your user will appear under Enabled Users on your environment.
Click on the Assign Security Roles button.
I forgot … You need a System Customizer role to be able to create your own entities.
More info is here: https://docs.microsoft.com/en-us/ai-builder/security