So you will need to use custom actions or zapier here to get this working properly. To get this working you will have to “pre-register” each invited user with the email address provided and a temporary password. Also set up an action here to update the logged in user and attach a relational property to that user with the user being created.
Then send an email to that person that they are invited etc and give a link to login to the app with their login credentials that have been generated for them.
Once they login, you should set up a link to a new screen to set a new password (for security). You can use a conditional action to do this only the first time they login. (or set it up with a boolean property (true/false) that they have in-fact updated their password.