Change database ownership on Postgresql Database As A Service Public cloud

Hi,

I tried the new Database As A Service.
I launched a PostgreSQL database, which has a admin user.
I managed to create a new database with the IHM (db-user1) . I managed to add a user user1 (don't really get the roles things) but I didn't manage to change ownership or give right to user1 on the database. When I connect with user1, I can't read the table "ERROR: permission denied"

On a PostgreSQL instance, I would go on psql to manage it but I don't find where I can do it with this new service. Could you help me ?

Best regards,