I'd suggest uninstalling the Windows Store Spotify as described here, downloading the offline installer and trying that.
Maybe before you run the installation, turn off your internet access?
I read more on that and learned that once an user has installed the store version, it's difficult to get rid of it and get the app installed as standalone version.
If you have Windows 10 Enterprise or Education, you can actually lock Windows Store to stop it from opening, thus you can install standalone Spotify app. Nothing usefol for Win10 Pro though...
Let me know how it goes 🙂
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