It's best to see inside this so you can see how it works. Otherwise, to play the project you must first register a password then login using that username and password (not case sensitive). This project also makes it so that only a single username and password can be created. If you want to test it and see what happens if you do make multiple accounts, just go to the Register Password sprite and read the comment that is there.
Just note that cloud variables are not actually enabled, this is just an example of what it would look like if you did use cloud variables and lists. Also, all of the variables and lists with "*Cloud" in their name, those mark that the variable would be in the cloud if cloud variables were enabled. So when cloud variables come out, just replace all of those variables with actual cloud variables/lists. btw, this isn't really meant for love-its or anything, this is just a demonstration.