As the topic says, now that the Garmin 1050 is a MTP device and won't mount a volume on a Mac desktop, how do I modify startup.txt so I can add my name, email and phone number. That's what I have done for my previous Edge computers.
What problem are you having? Do you see the Edge 1050 in Explorer? Note you cannot directly edit the file, you need to copy it to your computer first, then edit the copied file and finally copy the modified file back to the Edge 1050, overwriting the original one.