When you need to test builds on devices, or your project is ready to release to the public, you will want to make platform specific build bundles of your project. Before you do, make sure you have the correct settings for each target platform setup in your game.project file. Defold will attempt to use builtin defaults where it can, but for some targets you will need to setup certain files such as certificates, provisioning profiles, and, in the case of iOS, launch screen images to properly run.