It's a little hard to do guess-work, but I can make one at-a-glance guess at least.
Inspecting the mod files, I see you have some files under \Mods\Scourge_Class_4fd1a0ba-3ce9-448b-ac8c-da6a14c8a2e5\Story
which to me implies you've tried to tinker with the Story Editor at some point. However, I don't see any story goals. So you've perhaps generated definitions in the current engine without an updated story header. The current engine data is out of sync with game data, so here's a copy/pasta from the #Modding-resources channel that Raze linked:Experimental fixes for the current shortcomings of DE2. (By Nordbyte)
Place them in `\Steam\steamapps\common\The Divinity Engine 2\DefEd
I can't see anything immediately glaring at a glance through extracted files. Am I right to understand it happens only in multiplayer? Is it something players have reported? Have you ever experienced the crash yourself or been able to reproduce it?
Is there any recurring detail, such as always crashes in a specific location, area, or at save/reload, etc?