How to install mods/ good mods on Project Diva Mega Mix +

So I have Project Diva Mega Mix + on my Lenovo laptop. I don’t have a proper pc and I know a laptop isn’t the best for Project Diva, and it’s a little laggy on some songs, but it still functions. I have absolutely 0 experience with computer stuff and mod downloading. (The only thing I’ve managed to download is a Sims 4 mod 😭) I purchased an extra song pack on Steam (where I got the game) but I just want more songs and more stuff in general. I’ve been seeing lots of mods on GameBanana but I still don’t exactly know how to download them or where to put the file/ download or whatever on my computer. If anyone knows maybe good YouTube tutorials or good mods that I can watch or download that would be awesome!

Also while I’m here, I might as well say another issue. Ever since I’ve been playing Project Diva on my laptop, I use a PS4 controller to play. I use my PS4 controller cord, plug it into my USB port, and it connects. It works just fine but the buttons are swapped. The X button and the circle button are switched. It’s the same for the square and the triangle button. For example, if the song says to press the triangle button and I press the actual triangle button on my controller, it says it’s wrong. But when it says press the square button and I press the actual triangle button it says it’s right. But what’s more weird is on the left of the controller it has the arrow buttons but those ones are actually correct. Up is triangle, left is square, down is X, and right is circle. The slider notes work just fine, it’s just my buttons that don’t. If I try to change the controller buttons like in the editing part, let’s say to the arrow ones, it’s still wrong. I’m not sure if it’s the game itself or if it’s just my controller. I’ve actually gotten used to it and I’ve just been playing Project Diva on my controller “wrong” even though it says it’s right. I just want to know if someone else has had this problem or has seen it before.