The app is not a Microsoft approved app - error message

If you receive this message, you can quickly change this under the settings so that you can install your purchased software without any problems.

Open the settings and go to Apps.

In the "Apps and Features" you can select different options under "Select sources for retrieving apps". In your case, it would now say "Microsoft Store (recommended) only".

3. now please go to "Microsoft Store (recommended) only", there you can select "Everywhere". Now you can install your purchased software without any problems.