Things to make sure -
You are running the "Server" and Using "Aki.Launcher" inside your Tarkov Folder.
Try running them both with antivirus / Firewall disabled (if still having issues, turn them back on!)
Then,
I have been told that uninstalling and reinstalling ".Net" Programs helped with weird stuff like this,
Try to download -
* SDK 5.0.406
*.NET Desktop Runtime 5.0.15
*.NET Runtime 5.0.15
from - https://dotnet.microsoft.com/en-us/download/dotnet/5.0
I'm not sure about *ASP.NET Core Runtime 5.0.15
but if all fails, try that too.
(Make sure to download the x64 Versions)
Other than that, can't really see much without screenshots / Log files
just have to shoot in the dark here.