In order for you build to be available as a Development Project so that external developers can download and run locally with the Source Code, you will need to follow these steps:
1) Click on the Build version button, in order to create a new build that supports the Development Project feature:
2) A popup dialogue shall open:
Select the desired build type, and click on "For Plugin Developers":
3) Select the checkbox for "Build Development Project":
4) Click on the Build button.
Now, once you enter the created build, you will have the option to select both the standard "Debug Version", but also the "Development Project".