BigBusiness Extras help you build a new Data File, which is easiest using Single-User.
Single-User is Big Business for one computer, only, for testing, evaluation, or solo use.
Mac Single-User on Downloads includes a BigBusiness Extras folder with starter files.
Once you have built a new Data File, you might copy it to Server and connect Clients, for multi-user access, or continue running in Big Business Single User for just one Mac.