Creating an new account by email invititation not possible from app

After receiving an email invitation to create an account to a MM server, I am able to create a new account by proceeding to use the browser, but if I choose to use the mobile app (android in my case), the app defaults to the login page (user/email + password) and does not allow a creation of an accout within the app. Is this expected behavior?

I can confirm that - I think this is just not supported at the moment, so please use your browser for the user creation (do not check the “always open in browser” checkbox) and then you need to manually set up the user profile in the app for the time being.
Let me try to find out if there are any plans to add the signup screens to the app.