RushFiles works by detecting changes on files.
Because of this, using a database system like MS access or similar, that is not a database server system, but a local file getting changed all the time, is not a good idea.
Most of them are not designed to be used on a shared system where the file can be accessed from multiple users, and the file is online/offline at the same time.
Using them will result in conflicts and corrupted databases, as these programs write directly into the files and don't respect the normal update / create file operation system.
In short: Don't use Access or other file-based databases on sync-and-share systems.
Use the database on a local Drive (like C:), and copy the file to the RushFiles folder after it is updated, and the database program is closed.
You can also set up a scheduled copy of the file.