The app will only let you download restricted content that is attached to your account. Based on the screenshot, it looks like the developer just generated a publicly accessible download URL for the game. Those are not compatible with the app. The developer will need to generate a key that can be claimed so you can attach it to your account, then the app will allow you to access the files.
Thanks for the suggestion i tried both itch://library/ and itch://library/owned doing a right click on the game -> install and i’m not presented with an option for the premium variant in the drop down menu. A left click on the game leads me to game page where problem is the same.
https://itch.io/my-purchases and https://itch.io/my-collections just lead me to the payment confirmation page see below.
I could not figure it out using your instructions. If i did not try what you had in mind can you either be more detailed?
If there is any other information you need or some way i can assist please ask.
Stable 80705 (1f2c0bc)
Host 0.0.14
Linux 64-Bit (5.3.11-100.Fc29.X86_64)