VERY FRUSTRATED! Cannot seem to use MuseScore on multiple Apple devices!

I have a PRO account listed in my Apple App Store for MuseScore. My Apple ID is not the same ID that is showing up here on Support as my account. I have a Mac Min, an iPhone and two iPads. I want to link my same ID to all devices but cannot. I try and sign in and on all three and I get different IDs and on NONE of them does it show my payment or that I have an active PRO account. This is one of the most frustrating pieces of software I have run into in years. Should I just cancel my order and demand my money back? On my desktop Mac, I am logged in with I assume my Apple ID. I try and do the same with my other devices and though I login with Apple it does not ever show my purchase!