Difficult for us to fix this one, without access to a machine with exactly the same setup and access rights are yours.
eaDocX needs access to the .NET files, as that what we use for our user interface, so they are quite important!
Can you determine which part of the application is causing the error?
Also, try the Installation Verification test:
EA menu | Extensions | eaDocX | Help | Check installation.
This tests the lowest-level EA and Word interfaces, to make sure they are configured OK. You should get a very simple Word document produced. If this doesn’t work, then there’s no point continuting until the problem is fixed: eaDocX can’t talk to EA or Word.