Issue:

Downloading the most recent file with 1.16.4 compatibility will not allow you to launch with Minecraft 1.16.4 or FML 35.
Checking mods.toml file, it still only has versionRange="[1.16.5,1.17)" and versionRange="[36,)".

Possible Fix:

Tweaking the mods.toml file to add support for 1.16.4, and FML 35 allows the mod to load and operate correctly on 1.16.4 and FML 35.1.37