The database should be split - the data in tables in the backend (BE) and located on a server where users have access and everything else (forms, queries, reports, modules) in the front end (FE) and a copy located on each users local machine.
Unless you clarify why not, the pdf's should be in a folder on the server - perhaps in the same folder as the BE
and you don't need any code with regards what to show
in a textbox control in the detail section, put
=Dir(ContractPath & [ABC] & ".pdf") <> ""
change names to suit.
And in the controls format property put
;"Yes","No"
if you want colour use
;[Green]"Yes",[Red]"No"