Are you not getting an error screen that explains this better? There's supposed to be one.
Nevermind, that only works when mods properly list their dependencies, which DarkUtilities is not doing.
Is there anything special about any of the folders in this path?
C:\MultiMC\instances\1.16.2-home\.minecraft\config\forge-client.toml
Any symlinks or anything like that?
Please provide the debug.log of both your client and the server (more info on where it is and how to provide it in my signature below, just expand the spoiler)
Installer rather than launcher, yes.
But you are supposed to be getting Jar files, if you have Java installed and set up correctly double clicking those files will tell Java to run them.