I haven't tried this myself with Vivoactive 3, but the way I used to do it in a previous watch on Windows was to use Windows Media Player. This is on my Windows 10 (not sure if it's on every version these…
I haven't tried this myself with Vivoactive 3, but the way I used to do it in a previous watch on Windows was to use Windows Media Player. This is on my Windows 10 (not sure if it's on every version these days). I know I never use it anymore because when I fired it up just now it ran the first-run screens.
The way you do it is to create playlists for your music, then find the Vivoactive in the sidebar and right-click to set up a sync then choose those playlists and it manages it for you.
Syncing playlists to plugged in USB devices is about the one thing WMP is useful for after you've found VLC.
You can edit the playlists from VLC so that Garmin Express recognizes them: Just open the m3u file in a text editor and replace every "%20" with a space " ".