WinRAR is just a file extractor tool. It unzips your files so that they can be used. If you just place zipped files into folders, you're going to run into problems.
If you open WinRAR you will find all your downloads the same as if you open file explorer.
I would suggest that you start over. Make sure you follow the instructions in the videos exactly. You also must have a legit copy of GTAV. I mostly use@BlueLine Vibes as he has a vast library of diverse and detailed tutorial videos. I recommend sticking to one YouTuber until you know what you're doing. I say this because they will likely go about things in a consistent way and that will ensure you are doing things in a consistent way.
It is nearly impossible to help you here with such a broad problem. The only advice I have is to start from scratch, pick a YouTuber, and start from the beginning. Also, don't forget to show them love so they can continue to produce content for the community.
Good luck.