Don't use gateway at the moment. At the moment it is very tricky to get gw working at all. With b9s and the newest luma plus 11.4 firmware it is currently not possible to do this.
If you are not experienced enough to understand things you are doing when following a tutorial then just don't use gateway and only use luma and install games through cia.
The gw team needs to provide an update hopefully in the near future.