Since Oracle APEX 5.1 there's no way to create an application based on the migration project. The button that they referred on the documentation doesn't appear in the new version:
On Application Migrations page, click the project name.
Click Create Application.
The Generate Application wizard appears.
Yes, that's correct, that functionality has been desupported with APEX 5.1 - as outlined in our APEX 5.1. Release Notes, section 1.7.1 "Desupport of Migration Project Functionality":
Your best option is to utilise the Migration Project to analyze your Oracle Forms application, and the use the Create Application Wizard to generate a new application on the underlying database objects.
Regards, Hilary Oracle Application Express Development Team
