It infact was the antivirus program BitDefender. This is a bit weird, since I got that installed on my laptop as well, and the program runs fine on there, but who cares. (Edit: Firewall added Bannerlord automaticly) Thank you for your support.
I activated the firewall again and added Bannerlord to the list of programs that are allowed to access and change safe files. If anyone is reading this because of having the same problem you have to open the "Bitdefender Total Security" dashboard, go to "Protection", go "Safe Files" and then click on "Application Access" and then add Bannerlord as allowed, this fixes the issue.
