The phrase “Immersive Engineering mod Fabric” is a common compatibility search, but the file included on this website declares NeoForge as a required dependency.
What the included file declares
Inside the JAR, the mod metadata uses the NeoForge mod descriptor and requires the neoforge dependency. That is the most reliable indicator for the loader required by this specific file.
Why a Fabric profile will fail
Fabric and NeoForge use different loader ecosystems. A JAR built for one does not become compatible with the other simply because the Minecraft version number matches.
How to avoid a loader mismatch
Check the loader before downloading a large modpack or moving files between profiles. Keep separate instance folders for Fabric and NeoForge so files are less likely to be mixed accidentally.
What to do if you already mixed loaders
Remove the incompatible JAR from that profile, restore the correct loader-specific mods, and launch again. If the profile is important, make a copy before changing many files at once.
Next step
Once your setup is stable, use the other guides on this site to plan power, wiring, performance and larger factory systems. For the file itself, use the main direct download section on the homepage.