However, since it is not a final release, players have to enable snapshots to download the pre-release 1. Follow these steps to download Minecraft 1.17.1 pre-release 1: Open Minecraft launcher.

Minecraft How to download Minecraft 1.17.1 Java Edition update, which is expected to release on July 6th ...

To download the OptiFabric 1.17 mod, head to Curseforge and download the file from there. Do note that the project does not have Optifine, you have to get it separately.