This template is very easy to reskin, You will find a PDF User guide in this pack. which includes Eclipse And Android Studio and Xcode steps by step to import the project and export apk file. for more information check out these guides on buildbox.
In order to do any major gameplay changes, add levels, enemies, etc, Buildbox is required. On the other hand, you'll be able to reskin the objects, change menus, update AD Ids, and much more without having Buildbox installed. You'll find a documentation file that will guide you.