Hi Mo,
So, in order to give a user Administrative privileges in DSpace, you'd have to do something like this:
1. First login as that user via Keycloak. This will autocreate their user (Eperson) in DSpace
2. Then, have an existing Administrator login and add their created EPerson to the "Administrator" group in DSpace. (If you don't yet have an existing Administrator login, you can create one by using the "./dspace create-administrator" commandline tool)
In the future, I think roles will be inherited...but this feature doesn't exist yet. There is a ticket for creating this feature though at
https://github.com/DSpace/DSpace/issues/8406
Tim