Welcome back Prachi, • Both will need to be on the same version of AC so
either she upgrades or you install the previous version (which should
not be a problem). • You don't need a dedicated server for TW though it
helps but if you are working remote...
Looks like you are trying to open a file made with the current version
of Archicad (25) with a previous version. Solution is to download AC25.
Alternate solution to get another user in your office to open in 25 and
save as the previous version (24). ...