So maybe contact the folks at Smart App, and find out why?

Or is that a code word for a Windows control thing? In which case, log in as administrator, and install the app. 

No this means that that the developers at Sonos use a signature for their app that is not trusted by Microsoft.

I am the administrator, the setting is useful to stop malicious or untrusted apps from being installed.

Smart App Control is one of the weirdest Windows features, ever. You can only enable it when installing a fresh copy of Win 11, and if you ever disable it, that’s it, its gone forever.

Makes it damn difficult to test code against.

Install my Windows app instead (see profile), Smart App should be happy to let it in as it is a Store app.

It really is not that hard to test, you just need to install a VM with it activated and have a checkpoint before you deactivate it :D

Anyways I would rather have the official app fix their signature before I get a third party app.