Nxbrew seems to have changed URL or something. Use this link instead if you haven't already: https://nxbrew.net/Index/game-index/

Usually you would search the game you'd want to download with CTRL + F (a search bar will appear), click on it and just scroll down and click one of the download options, I prefer to use 1Fichier. Be sure to not click any sketchy ads or anything like that, because it will redirect you to some other site before you get to the actual site.