Permissions on home directory

[AdamWRichardson]

I've tried creating a distrobox container using home located on an external USB but when I try to enter I get an error when trying to copy from /etc/skel: cp: cannot stat ... permission denied

I've checked the permissions for the mount point and I should be able to write to the directory so I was a little confused as to why distrobox couldn't. What are the permissions needed for an external home directory?

(FYI I have also tried this with distrobox v2 and it didn't work either, I couldn't debug it though because the --verbose flag is broken)