Hey Kyle - all of the Ride With GPS routes that we post have the option of downloading as a gpx file. When you open a route, if using the RWGPS (Ridewithgps.com) Website - you'll see an option on the left hand side that says "More" - click the down arrow to open that - then choose "export as file" - you'll be given several choices - pick what works best for your watch.
If you're using the App - you'll need to sync your watch with the app - RWGPS has a great "help" and "FAQ" section that should walk you through linking your watch with the RWGPS App.
I do not have any experience downloading maps from Strava or MapMyRide - perhaps someone else can chime in here.