In past, I've built many environments, I know how to add users into them and grant them permission.
but now it doesn't work anymore, I built a few new environments (me and some of my colleagues) and we add a new user and get the below message, but nothing happens even after a few days.
Which user do you want to add into your environment? An external user or the member user in your Org?
Currently, the Security model has been changed in PowerApps and now is managed by Dynamics 365 user management center.
If you want to add an external user (not in your Org) into your environment, I afraid that there is no way to achieve your needs in PowerApps.
If you want to add a member user (who are not in the list of users in this environment) of your Org into this environment, you need to type the email address of the user, in your organization, then click "Add user". You need to Wait for a few minutes to check if the user is available in the list of users in the environment.
More details about configuring environment security, please check the following article:
Please click the "list of users" link button to check if the user you want to add into this environment is existed within it.
If the user is still not existed in your environment, please check if the account of the user (you added) has been removed/disabled from your Organization.
Thanks for the reply,
I know "how to do it" as I said in my original post that: "In past, I've built many environments, I know how to add users into them and grant them permission."
I have done everything that you said in the last few days, but instead of a few minutes, it actually takes "forever".
Apparently, there is a bug/issue in your system, if you like, you can contact me and shadow my screen.
the users are real users from my company, I can see they are NOT disabled, as people are using them and email me from their account.