You can download Shivaxi RLCraft on the Twitch Launcher, Techniq Launcher or the RLCraft.CC Launcher!
Download Shivaxi RLCraft 2.8.1 for Minecraft 1.12.2
To play RLCraft you need a bought copy of Minecraft Java Edition, if you already have a Minecraft account you can choose your preferred type of installation down here.
Make sure you save the download to a new folder somewhere. Don't just place this on your desktop or run it from your downloads folder, it should be run from a folder of it's own.