The program is in Reader mode and needs to be activated. Go to Help > Activate and enter your Customer Number (note that it cannot be a Trial number, which starts with EFDT / XFDT / 9FDT). Click Activate and once the activation is complete, all program functions will be enabled.
For further assistance with Final Draft activation, dial 818-789-6281. This is a 24/7 service.
See also: After I enter my Final Draft Customer Number and click Activate, I get a message saying the number is invalid.