You have to click on "download now" button. Then it will ask you for a price. But, there is wroten "Just take me to the download" or something. Then you click on download (windows version, ofc).
It will download a zip file. Open it. Click until it appear a file called "Gacha Club Edition.exe" or something. Then open it. Click "run all" ( idk how it's wroten, I'm from portugal :']) and, if it appears any file, click "ignore". When it ends, open the file called "gachaclubedition.exe". DONE!!!