Android can save the Everdo Pro key file from email as blahblah.key.txt. This works for Android, but Linux and presumably other OS are looking for just .key. Edit file name and it works fine
It’s strange that the the files extension is being altered, I have never experienced that. Possibly it’s related to the email client app on Android.
Most definitely the email app/android defaults are the issue. Easily fixed, but frustrating to users who aren’t aware that various systems handle basic things differently.