Photomator Lifetime License Not Restoring

I purchased a MacBook Pro today and I've downloaded Photomator. When I go to restore my outright purchase I get a pop-up saying 'subscription not found'. It works perfectly fine on my iPad and my iPhone. I can confirm that I am using the correct Apple account, have tried restarting and reinstalling the app. I purchased the outright License back in 2020 before they implemented the subscription model. Has anyone got any information as to why it's not allowing me to restore my purchase?