RAM slots are inside your computer box. The more RAM you have, the more programs you can have open at once. RAM looks like a bunch of microchips on a long, skinny PCB. Your motherboard will have so many RAM slots for you to put RAM sticks in, after you fill them, you have to buy bigger RAM sticks and get rid of the old ones to get more.
The reason nVidia told you there was no compatible hardware is because nVidia software is designed for nVidia hardware. You can't install it unless you have a nVidia graphics card.

Keep in mind that you have to meet the minimum system requirements in all areas to play the game. That is, you need to meet the graphics card, RAM, CPU and disk space requirements.

Edit: I lose.