Install, launch, and check the menu
Put compatible Litematica and MaLiLib files in the Minecraft mods folder used by your Fabric installation. Start the Fabric game profile and open a world. Use Litematica’s configured menu key to check that the mod loaded; if a key does nothing, inspect the game’s controls for a conflict rather than assuming the file is broken. Menu names and default bindings can vary by mod version.
FIRST CHECK
If the Litematica menu is unavailable, fix the installation before trying to load a schematic.