How long is a piece of string?
If the database is structured correctly, and the code is written well,
and all the users are doing queries (not updates), and the network is
fast and reliable, Access can probably handle "in the order of" its
specified maximum number of simultaneous users.
Conversely, if the database is not structured correctly, or the code is
written badly, or most of the users are doing updates (not queries), or
the network is slow or unreliable, then, Access might expire with a
very small number of users.
Pay your money and take your choice!
HTH,
TC [MVP Access]