Brad, i don’t really understand what your issue in this topic is.
From what i understand you have a mobile project, which runs a server action from another (API) project that logs the users in. So what is not working exactly?
Isn’t the user logged in when you enter the username and password in the login server connect form of your mobile project and submit it?
Also, you can use the login step as a value for a setvalue step in your login action to output the logged user identity.