Fallout 76 doesn't open on HDD

I dont understand what you mean can you be more specific please?

Did you authorize the game to access your account info via the usual popup?

I understand. Well, deleting your Fallout 76 saved data files can resolve some errors. Please be aware that while deleting the save data, it will reset your Options settings, and no character data or game progress will be affected, this will delete all saved photos and they will not be restorable. Make sure to back your photos up before proceeding.

Navigate to C:\Users\user.name\Documents\My Games\Fallout 76

Delete the Fallout76 and Fallout76Prefs configuration files

See if this helps. If Fallout 76 is not installed there, open your drive partition and search for Fallout 76 that you'll find the correct path.

i had that very same problem when i started playing fallout 76, and apparently they have a pacifism mode in the options, but get this it doesn't stop people from attacking you for no reason, instead it paints a target on your back, the community for fallout
76 at least in my short time of playing is either all little kids or toxic adults, killing you for loot, plus the game is just a broken mess, i have hope for the future of 76, but as is its just underwhelming.

Fallout 76 is an online only game so it's always required a subscription to play it. It doesn't have to be Ultimate, it can just be Game Pass Core (what was Gold).