Threema messaging app is not installing (parsing error)
Threema is a messaging app, it is not installing on /e/OS ("There was a problem while parsing the package").
Threema is a privaciy focused messenger. It is an app that needs to be purchased. On Android it typically installs via Play Store, but does not need Play Services for running. For users who do not have Play Playstore, the developper offers purchase via their website, in return the APK can be downloaded.
This APK cannot be installed as desribed above.
My Device: PocoF1. OS: /e/, Oreo, latest. Threema system requirements: Android 4.1+