Sonos and MyCloud Home

How do you add a folder on mycloud home to your Sonos library. There doesn’t seem to be an obvious way for folders to be seen by sonos. I am using a MyCloud home 3TB device with Windows 10. I can see the drive in my computer and mobile and add/create new folders. I go to Sonos and go ‘add library’ and then it gives me two options add folder or networked device. I have tried both and a host of different options and can’t get anywhere. Have I bought the wrong thing ??

Hope this will help, I don’t own a Sonos or My Cloud Home. I have a My Cloud and a Bose SoundTouch 10.

Thankyou so much! This is great. All sorted.