Hi @dj93882
As @OliverRodrigues mentioned, Using the Portal management app, you can assign web roles to your user.
To open Portal management for Power Pages
1. In the Power Pages studio > Click three dots on your left
2. Select Portal management .

3. Then follow the instructions from Oliver
Creating new web role:
1. In Portal management > under Security > Web Roles > Click new

Hope it helps.
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