Permission masks are additive- 4 2 1 0 (read) (write) (execute) (none) and the sections are [special][owner][group][everyone]
So read and write is 4+2=6, read and execute is 4+1=5, etc.
In the case of permissions its moot if 1 person or 10 access an account unless they're logins. In this case it appears you have 1 login (post) and two directories (money/assets).
So --
Make sure post exists as a user and as a group.
Code:
chown -R root:post {money,assets}
chmod 2730 {money,assets}
([special][owner][group][everyone] 2730= (Special:SetGID, Read/Write/Execute, Write/Execute, None))
A directory must have execute permissions for a user to be able to change directory something where that permission set is applied... so you need a 1 and you want the ability to write so 2, 1+2=3.
If jonn and jean had an account each you could add them to the post group and their users could write there but not read the directory.
If this isn't clear wikipedia has a good write up on permissions in unix under the
chmod entry.