I haven't used this, but it seems to do way more than the average person know how to use for an SMS app
Even in the readme, it says:
The technical functionalities of the app are currently not user friendly, which would be updated with the help of PRs and issues. The reason for the lack of user friendliness is solely based on the app aiming to be as customizable as possible. Users should be able to configure the app to their custom cloud servers without being tied into using specific providers.