The Sims 3 Free Download Setup

I've had the same computer in the time I've had Sims 4 installed and I have years of multiple saved games on (full of edited worlds and sims) but now I am in the process of getting a new laptop. I am wondering how do I go about the process of reinstalling Sims 4 on a new computer? And how (if possible) can I also transfer all of my save files so that I do not lose it all and have to start over?