Mac desktop says "Unable to download App" but the App is downloaded on the iOS device?

I'm on macOS 11.3 Beta (20E5172i) and have the same issue. I've bought an app on my iPhone and my MacBook appears to subsequently try to download that app. I get these messages whenever I download a new app on my iPhone.

I found this setting in the macOS App Store Preferences and disabled the automatic app download, but don't know yet if this fixes the issue.

For me, this was caused by a slightly overly aggressive disk cleanup tool (CleanMyMac). After cleaning up, the app store's cache was missing, but the app store kept trying to update, causing an error visible in the Console app.

The fix was to quit the app store and restart.

First attempt to update failed, but it worked on the 2nd try and I could see a new cache was created in: /Users/jsumner/Library/Containers/com.apple.AppStore/Data/Library/Caches/com.apple.AppStore/Cache.db