Version control is hard to explain succinctly, so
try Wikipedia.
Larian uses an industry-standard version control system called
Perforce, or P4, which is helpful for them but not so helpful when you don't have that system or a license. And, unfortunately, the Perforce plugin for Divinity Engine 2 does not seem to be disabled in code; the editor will crash if the P4 DLLs cannot be found.
Best you can do is ensure that
UseP4 is set to
false in
Config.xml.
edit: See JB's post above.