The game is not installed or downloaded via Epic, instead the Epic Games Launcher launches Origin to link your account to install the game. This can be done manually to still be able to install and download the game without the Epic Games Launcher.
Origin needs to be installed and working for this, please consult https://github.com/lutris/docs/blob/master/Origin.md for how to get it running on Linux via Lutris.
On Windows Origin just needs to be installed and ideally updated to the current version.