Where does the "adminlist.txt" file need to go on Ubuntu?

I have a virtual machine hosted on Microsoft Azure that is running Ubuntu 18.04. I setup a Valheim dedicated server on it using LinuxGSM. According to this guide, you need to create an "adminlist.txt" file and add the Steam 64 ID of the users you wish to be an administrator on the server. The guide then says the file needs to go into the root directory of the server, but I can’t figure out where exactly this is.

I tried placing the text file in /home/<serverUsername>/ as well as /home/<serverUsername>/serverfiles, but I was still not an admin within the game (this is after restarting the server as the guide claims). Where does the text file need to be placed on a Ubuntu installation of a Valheim dedicated server?