Troubleshooting

I can't run Archive2.exe / *.ba2 files are missing

Look into "archive2.log.txt". If you can spot "System.IO.FileNotFoundException: Could not load file or assembly 'Archive2Interop.dll'", then Visual C++ Redistributable for Visual Studio 2012 Update 4 is missing. Download and install it.

I've found the solution here, btw: https://www.nexusmods.com/fallout4/mods/28795/?tab=posts

"You need a new app to open this bethesdanet-link" dialog when launching Fallout 76

The bethesdanet:// protocol might not be associated with the Launcher. Try to reinstall or repair the Bethesda.net Launcher.

UnauthorizedAccessException / Access denied: "C:\Users<yourname>\AppData\Local\Fallout 76 Quick Configuration"

Please check if you have write-permission to the folder:

Right-click on the folder, click on "Properties".
Uncheck "Read-only", if checked.
Then click on the tab "Security", select your user profile.
Check if you have all permissions. If not, click on "Edit", and tick all the boxes except "Special permissions". It should look somewhat like this (Screenshot).