You can be invited to a multiplayer room by an anonymous shared link or by explicit invitation. How you join depends on what kind of invitation it is.
Shared links are anonymous access to the lesson so there is no need for credentials.
Mobile
a.) If you have the app: it will launch you straight into the app
b.) If you don't have the app: it will take you to the app store where you can download the app to continue
PC
a.) If you have the app: Allow the browser to launch the xplorer player program and it will auto launch the xplorer player desktop app.
b.) If you don't have the app: click on the windows download badge to install the program.
c.) Click launch in web to launch the WebGL version
If your account was invited to a multiplayer room you will receive an in-app notification as well as an email.
Next: Presenting a Lesson