Dynamics GP 2018 wrong version of GP2018 Power Shell included
Be aware of an issue with the GP2018 installation media
You can see above that the installation media MDGP2018_RTM_DVD_ENUS has under the Additional Products the GP2016 installer for Power Shell.
The correct installer has been provided by Microsoft under Customer Source here: https://mbs.microsoft.com/customersource/northamerica/GP/downloads/service-packs/mdgp2018_dexterityreleases
It is not obvious that a administration module should be under something as specific as Dexterity Development System – buy hey at least it IS available!