Setting up Immich to store all photos and videos on my external harddrvie on Umbrel OS.

So I have a 2tb Umbrel home server and with the new files update this year and support for external hard drives. I want all the photos and videos that are backed up to be stored on my 4tb external harddrive. I went to the faq's but I'm stuck. There is so .env file on my Umbrel OS Immich folder. I just need complete help.