Working with Git
Don't know what all this "git" is? No worries, you're in good hands. Take a free journey to code school!
Working with Unity
Open the "The Drop Zone" directory as the project in Unity (not the root dropzone repo). Note the gitignore ignores a lot of files normally visible in a project; this is expected.
Building
Builds should not be managed under version control. Exporting to the "Builds" directory will satisfy this.