Lightroom Mobile Premium allows access only on Mobile.
Lightroom plan with 1TB (available at Mac app store or adobe.com), provides access on both Desktop and Mobile.
You should cancel Lightroom Mobile Premium through your iOS App Store subscription settings, since it seems you need the plan that allows the Desktop app.
If you bought a subscription for Lr Mobile for your phone then you may need one for the Lr Desktop program for your Mac computer.
Best thing to do is log into the Adobe main website and check your Adobe ID subscription status. If it lists Lightroom you may only need to install the CC desktop app and then Lightroom desktop on your Mac.