Download the Wurst-Client-v7.15.3-MC1.17.1.jar from the official Wurst Client website .
Open the Minecraft Launcher, select your Fabric 1.17.1 profile, and hit Play! Safety and Fair Play Download Wurst v7.15.3 MC1.17.1
Don't forget to download the Fabric API mod and place it in your mods folder. Download the Wurst-Client-v7