Big Business 7.1.1 updates the database, so updating Server requires updating Clients, too. Mac Clients using a Mac Server can update themselves by clicking Update on the dialog that says "the version number of the server application is more recent than the version number of the client application. (6198)
If you update to Big Business Server 7.1.1 for Mac, Mac Clients can update themselves by clicking the Update button on the dialog that appears when they run the "old" Client.
This feature works for Standard, non-Administrator users, too. This feature does not work for Windows because of its security settings.
Download and install the new Client for Windows, for Macs connecting to a Windows Server, or for remote users where updating might be quicker.