WARNING:
As described, putting the database on a server and letting users access it from their workstations is TECHNICALLY NOT client/server architecture.
This is client/server as in FILE SERVER client/server. BUT NOT database client/server.
In the sense of ODBC, Access is more often the CLIENT than the SERVER. In fact, I've never personally seen Access set up as the server side of the equation. You use SQL Server or ORACLE or some other product for that. Then Access can be the client side of an ODBC connection.
When you put a .MDB file on a server and let users connect to it, they must first have a local copy of Access. After that point, you can grant users permission to work with the (now shared) files on the file server.
You do NOT need anything but the file on the file server and local copies of Access to make this work correctly. HOWEVER, to optimize performance and assure data security, you need to search this forum to see topics such as
Split Database
Front End/Back End (and variants such as Front-End/Back-End, FE/BE)
Workgroup Security
Securing a Database
Windows Security
One more issue, and this is a minor tweak - your first post was at a very early time and you "bumped" the thread only 80 minutes later. Please allow for time zone differences. Patience is a virtue here. You got a response 4 hours later, which for this forum is not really that bad. Many posts go without a response for two or three days.