I launch my game offline using a batch file so that i can have separate online profiles for online and offline for easier access to mods. I own the game in epic games.
Check your batch file then, the game seems to think you don't own an epic games account. Start the game through the launcher and look in EpicGamesLauncher.log in the folder C:\Users\%USERNAME%\AppData\Local\EpicGamesLauncher\Saved\Logs for the correct way to start the game.
