Share Public Folder Only or Airdrop

Linux isn't Unix and macOS is based on Unix, but does some things differently (e.g. accounts and passwords).

For each account, I see the name on the account, but I do not see what the usernames are on the accounts.

You enter the account Username when you create the account.

I don't know of anything in the default setup that has everyone read/write except /Users/Shared.

If you have folders that have everyone read/write except inside /Users/Shared/, you created them with those permissions.

any account that could access that folder would also be able to access all the other folders on my mac with read or write privileges turned on for "everyone"

The actual permission title in Unix is 'others' meaning other users that have a login to the computer.

Everything inside of your Home folder has everyone 'no access,' so even if you give them a login to your Mac, they cannot see inside the subfolders of your home folder (except Public and Sites).

If you create a subfolder in your Home, it will inherit the permissions on your Home folder with includes group/other read only. If you did create folders immediately inside your Home folder and want them secure, you need to delete the group and set everyone to 'no access'

The client version of macOS isn't particularly suited for multi-user file sharing/collaboration.

If they connect as "Guest" then they can see into anything shared out in Sharing Prefpane that has everyone at least read.

If they connect as a user on your Mac, they will have access to everything that account has access to.

If they connect as a Sharing Only user, they will have access to everything you designate in the Sharing System Preferences. You can put users into groups if you have differing access requirements for groups of people. In that case, you should probably be running a file server. However, a group can be useful if you need all the users to be able to open/edit files other users create. You can set an ACL that will allow that and assign to the group (remember where I said client macOS isn't particularly suited for this).

Create Sharing Only users for others to log in with:

1. Open Users & Groups
2. Click padlock to Authenticate
3. Click the + button
4. Change the type of account to Sharing Only
5. Enter username/password and account name
6. Click Create User

Create Groups

1. Same as above only change the type to Group, there is no password, and click Create Group.
2. Add users to the groups

   Select the group in Users & Groups, then check the boxes for the users that belong to the group.

How to set up File Sharing

1. To enable File Sharing, check the box in the Sharing System prefs.
2. In the Options, make sure SMB is checked.

   If you have computers running pre-Sierra, you might need to enable AFP, also

3. Add folders to the folders list by clicking the + button and browsing.
4. Add users/Permissions to the folder
   1. Select the folder in the list
   2. Click the + button under the User list
   3. Select the desired user (group) from the list
   4. Set the desired permissions for that folder/user (group) combination

The File Sharing section will show the address for the other users to use to access your Mac (if it doesn't show up in the Shared section of their Sidebar).

When selecting a Mac to connect with in the Finder, it will automatically attempt to log into that Mac as the user they are logged in as. I don't remember what they will see when that fails (assuming they don't have a login on that Mac).

Eventually, they will need to Connect As… and use Registered User and the Sharing user info you created.

If you use Connect to Server (cmd-k) you can use this format:

smb://username@IP.Address, or afp://...

If you need collaborative access for each user to edit other users files, request that info and I will post the directions to do that. You will need to create groups to use it, and also create folders for each group (preferably in /Users/Shared).

For AirDrop to work, you need both WiFi and Bluetooth turned on. And, since it uses Bluetooth, the two Macs must be fairly close (10m maximum with no interference).

You can set up File Sharing such that you create the user/password that can access a single folder, including your Public folder, if you like. If AirDrop cannot be used, then post back and I can tell you how to set up File Sharing.

If using the file sharing route, do the users need to put files and get files from the shared folder? Do you need to put files and get files off the other computers?

It sounds like you have several networked Macs. Do you not have a file server set up, independent of all the Macs?