how to install capsule on win 10

This depends on what version of the Time Capsule that you have.

If you have the current "tower" or "tall" shaped version of the Time Capsule, the product is unfortunately not officially supported by Apple when used with Windows software, although some users have reported that they are able to make things work OK.

A better plan would be to use a Mac or an iPhone/iPad to set up the Time Capsule.

If you have the older "flat" or "square" version of the Time Capsule, then you might be able to use AirPort Utility 5.6.1 for Windows to set up and configure the Time Capsule. But, note that this version of AirPort Utility was introduced during the time of Windows 7, and Apple has not updated the application since that time. So, it may or may not work well with the Time Capsule.

Download AirPort Utility 5.6.1 for Windows - Apple Support

Sorry, I don' have Sonos so cannot say how well a Time Capsule might work for that purpose. You may have better luck posting in a Sonos support forum. Or, you could start a new post and use Sonos in the title to attract the attention of other users who have installed Sonos systems.

In general though, the TC does not work very well if you are asking about moving the iTunes Media Folder over to the Time Capsule drive and storing your media there. Access to the media is slow, and the library tends to get "lost" on a regular basis, requiring that you restart your network to get it back.

I have 2 homes and 2 MacMinis that are logged in to the same Google Drive where my iTunes Library reside. Music additions are then available in both locations. How can I accomplish this with 2 Capsules? I could use iTunes if it can be connected to the capsule?

Do you have both basic parts of iTunes residing on that Google Cloud drive? That is do you have both the iTunes Library AND the iTunes Media folder located there? As you may already be aware, they do not need to be co-located. The iTunes app can be "pointed" to which Library to use at startup. In turn, the Library points to the Media Folder.

Having these two components on a Time Capsule should offer better performance compared to having them on a Cloud drive, but as Bob has already mentioned, the TC (as a media storage device) will not be significantly better.

It would help to understand your goals with using iTunes.