How can I limit what drives I am sharing in File Sharing?

I have an external drive that I want to share on our LAN. I have enabled File Sharing in System Preferences and I have added the drive to the Shared Folders area. For users I have added my own account, Staff, and Everyone. On another local Mac I am able to login with my account, but then I see everything on my Mac, including the external drive. I do not want this. I want to just share this external drive.

I tried setting up a new user through the Sharing preferences and set the password. Set the permissions for this user to Read & Write. I try logging in on the other Mac, and the password is not accepted.

I did this with another user, and the password was still not accepted.

I tried creating a new Group, added these 2 new users to the group, and then added the Group to the Users area in the Sharing preferences. No luck.

I click on Options in the Sharing preference pane and try turning on Windows File Sharing for these 2 new users. It won't accept the passwords I set.... I have also enabled Guest access on this shared external drive, but logging in as Guest on the other Mac does not work. The other Mac is an older iMac running High Sierra.

I am stumped. Does this not work on Big Sur? Or is the problem High Sierra/? Any ideas how I can get this to work?