@chris-43 What are you hoping to open the route with? You'll need an app that accepts GPX files to do that.
Unless you want to use MyRoute-app Navigation (which is a separate app from the regular MyRoute-app app). You don't need to use "Save as..." with either MyRoute-app app, as both apps will let you access your routes from within the app already.
If you're just trying to work on the route on your Samsung tablet through MRA Web, you don't need to "Save as..." anything, you can just work on the route like you do on your computer.