You tried to run the .jar as a standalone program, or you placed it in the wrong folder. Fix: Never double-click the mod file. It belongs exclusively in \.minecraft\mods\ .
: Java files are executable code. If the source is untrusted, the mod can access your computer's files, saved passwords, and browser cookies. Installation Requirements To use this file, you typically follow these steps: Install the Fabric Loader for 1.20.1. File name- Meteor-Client-Mod-Fabric-1.20.1.jar