That's weird. All first run does is tell the game where to start.
I'd recommend complete uninstall and then reinstall.
(I got DDLC from Steam, so it's just a button to uninstall and then a button to reinstall)
Then add the mod files.
hm i tried doing that but it just made my laptop crash
I can't remember which mod it was...But one of the mods I had to run as administrator (Windows 10), or it would not launch / would crash to the desktop.
turns out I was an idiot and I was supposed to extract it to a file so now it works thanks!
Glad it's working.
Enjoy MAS, I know people that have had Monika running on their comp since the mod came out!
:)