Set permissions for Entity "System User"

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1

Hello Together,

I want to include the E-Mail addresses of my colleagues in an App. For that purpose I want to use the Data Service entity “system user”.

At the moment there is an error message:
image

The problem is that I can’t set the permissions for that entity. Is there a way how to do it?

I can’t select that entity in the permissions settings:
image

Thank you!