1.Go to the home page scroll down until you see "DownloadFabric 1.20.1" open the link click download then click "download universal jar"
2.Open that jar file make sure you pick client-1.20.1 click install
3.Go back to the home page again and right below the link for fabric will be the "Modpack Download" download and extract the files from it (remember where this folder is)
4.click win+r and type "%appdata%" then click ok and look for a folder called .minecraft inside this folder should be your mods folder
5.take the extracted folder from earlier and move all the .jar files inside it into your mods folder
(i recommend increasing the maximum amount of ram for minecraft as its default 2 if you don't know how click here- he's a yapper btw)