That’s where the repository is for that particular app. I think all of the different apps tell you how to install, but let us know if there is one where you are having trouble!
Although, ODK-X Table sample app is fetched through server synchronization, while Longitudinal Clinic one is installed via pushing the files to the device. Are both same? I am not able to find the difference.
The Hope sample doesn’t have its own branch, unlike the other samples. The Hope demo is stored on the master branch of app-designer, which contains the Hope demo as well as other examples. At the moment the Tables demo (https://tables-demo.odk-x.org) contains the master branch of app-designer. So the content pushed via Grunt and the content on https://tables-demo.odk-x.org are the same at the moment but this might not hold true in the future.