Here is an email we received from Threema in regards to using their messaging app, on our devices.
Please deal directly for purchase and support. Thank you

CryptoCloud

Dear CryptoCloud

Thank you for your message and your interest in our communication solutions.

In our Threema Shop, licenses can be purchased for Android devices. After the completed
purchase process, the installation on the mobile device is done using an APK file. Please
find further information at https://shop.threema.ch/.

For commercial customers, we recommend using Threema Work, which is specifically built for
companies: https://threema.ch/en/work

I hope, that I could help with this information. For further questions, please do not
hesitate to contact us again.

— 
Threema GmbH
Churerstrasse 82, 8808 Pfäffikon SZ, Switzerland