Some lessons you may want to share to a specified list of users only. This way only users with the proper credentials can view the lesson, it is a more secure way of sharing your content with users.
First you must give users access to the project
Users added in this way cannot edit the project just view it. They will now beable to login to Modest Tree Xplorer and see the project in their project list.
If you want to send a multipalyer invite to specified users so that they can all join in the same lesson together:
All selected users will recieve a multiplayer invitaion they can then join in app or via shared link in their email.