Because in Garmin you cannot import a zip activity, but a tcx.
If you extract the zip file, it contains a .tcx file which can be uploaded to Garmin
Thanks Jeremy, yes Android does not support exporting TCX directly so we had to use zip file.
It would be more practical if we could avoid going through a zip.
Why not export to .fit like the Wahoo fitness app?
It would require a lot of development for us to support FIT as their is no native library in the technology we are using. You can connect to dropbox and then it is TCX file in DB, which should make it easier for you.
OK I will do with the zip.
You know that when you share an activity there are several files in the zip? It would be logical that there is only the tcx of the shared activity.