Question Epic games wants me to install the game again

Feb 1, 2022
I recently got gta V on epic games, i dont have enough space on my pc so i downloaded the files on an external hard drive. i opened the game and everything seemed fine so i closed it. the next day i plugged the hard drive in and tried to open gta but epic games keeps on saying that its not installed and when i open the epic games app, it says i have to install it. please help