Crash when executing a jar

This is not how it works, mods have to be installed into the .minecraft/mods directory. Mod loaders (e. g. Forge and Fabric) and some mods like OptiFine and Iris have an integrated installer, this is not the case for the absolute majority of mods, meaning they don't have any GUI that would run when opening them with the Execute .jar button in the launcher. If you don't know how to get into the .minecraft directory, please read the article on how to access it.