You can do that, but it doesn’t get you much. Set up https://tapiriik.com to sync between your Garmin Connect account and your Dropbox and you can get copies of your FIT files on your Mac automatically, but not into any of the software you use. rubiTrack is pretty easy, hit command-Y and it syncs whatever you’ve set it up to do. I have mine set to sync whatever is new in /Volumes/GARMIN/Garmin/Activities (since I use different Garmin devices for different activities and always plug them into my MacPro shortly after I get home) and with Withings via Internet for my weight from my scale. Golden Cheetah syncs automatically with Strava (and a few other places, but not GC), but I still have to tell it to get my weight from Withings. Nothing is quite automatic with the desktop apps. My flow on the Web is device -> Garmin Connect -> Strava and SportTracks (that’s automatic), and separately on my Mac device -> rubiTrack and Golden Cheetah and Garmin Training Center (all need to be told to sync for something or other). (And for my PowerPod, PowerPod -> Isaac, Velocomp’s Mac app.) I keep all of the databases for the Mac software in my Dropbox and use aliases if I need to (sometimes there’s a preference on where to look) to put the file(s) in the place where the software looks for them, so I can see the same information on my MacBook Pro that I do on my MacPro. No matter what you do there’s still some manual stuff you need to do (naming activities, designating equipment, adding photos to the sites/software that take them if you have any, etc.) everywhere.