Also, would I be able to do things like login to your account on any device via a username and password? It would probably be similar, right? And yeah, I don't want to spend any money yet, that's why I mentioned PlayFab
With PlayFab you can do Login, in fact you need that, but you will need to code the client side part using the PlayFab SDK if you don't want to spend *any* money.
With PlayFab you can avoid having to maintain your own server, do the backend programming, etc... But still programming knowledge is needed as usual.