Question about games saves

Hey,

I own a PS4 and a PS+ subscription. I was wondering, if I play a game on my console (primary) and then log onto my girlfriend's PS4, log into my account, will I be able to continue a game where I left it at on my console ? Can I do it through the cloud ?

Also, would I need to carry the disk of the game with me in order to play it ?

Kinda new to all of this, Thank for the help !