I have been using MRA seamlessly with a TomTom ever since MRA was released. Create a route on the Mac, connect the TomTom via USB, transfer the route to the GPS. Job done time to go for a ride.
As many others have found I was disappointed and frustrated to find that my new Zumo XT does not play nice with the Mac OS. After some searching I found Android file transfer but that requires Mac OS 10.5.x and my Mac is still running Catalina (10.15.x) so that proved a dead end. Finally it dawned on me that MRA is a web based product. Duh! (Forehead slapping moment)
The answer is simple. Create the route on the Mac (I prefer to do this on a big screen where I can see more detail particularly with complex routes) then simply open the MRA App on either my iPhone or iPad, open the route previously created and export it as GPX 1.1. The Garmin Drive app on the phone or iPad picks up the export and transfers it to the Zumo XT. Simple and quick. Really not any more difficult than connecting the GPS via a USB cable. I can and have uploaded previously created routes to the Zumo whilst sitting (stopped I might ad) on the bike.
I'm sure others have figured this transfer method out but I can't see it documented here hence this post.
I do have one request for the wonderful MRA people. When you create blog posts please specify which system OS the post relates to. The recent blog post about transferring routes to a Zumo XT makes no mention that the method outlined cannot be used with the Mac OS. The world is not 100% Microsoft centric and by failing to mention issues relating to other OS you cause a lot of unnecessary frustration amongst users.