Ah, okay. That did the trick. There's a bunch of mod errors I'll have to go through and fix, but forge is finally working properly! Thanks a lot for your help.
EDIT: I fixed all the mod errors it was giving me, updated the mods, etc., and now the game is crashing on launch, without any error screen. It loads the Mojang logo screen (and begins to load the mods with forge), but then closes and brings me back to the launcher.
Here's the new dropbox link https://www.dropbox.com/s/rebesfq16frpnou/SRGB - The Modpack 1.0.zip?dl=0
And here's the crash report.
crash-2020-08-21_12.04.46-client.txt