signin with invitation link
On signin screen, there is no way to signin using invitation link.
Currently, the expectation is that the browser to desktop integration should work and open the app.
If your platform is configured not to allow such integration or simply it is not available for any number of reasons, your only option is to use web browser (which comes with its own shortcomings; you can't make a test call and adjust camera/microphone etc. before the meeting..)