I can’t find the industrial foregoing's manual for Minecraft 1.16.4
Check to see if the mod is actually installed by looking at the title screen and clicking the mods button. If there is no mods button, then that means there aren't any mods installed. If there is a mods button, click it and look at the list of mods. Industrial foregoing should be on there. If it is there, then I suggest deleting the mod, reinstalling it, and putting it back in your mods folder.