Shauna-Rae Brown Just an fyi, looking thru the Table of Contents for the one-day, instructor lead class "Configuring Web Apps Using Web AppBuilder for ArcGIS" Although the majority of the class looks to be for WAB Online, it looks like they do touch on the developer edition in Section 5. Also take a look a the class reources.
https://community.esri.com/groups/esri-training/blog/2017/06/30/configuring-web-apps-using-web-appbu...
Although this would definitely get you started and help you decide whether you need the Dev Edition or not, I second Ken Buja 's suggestion of the recent proceedings and the videos from both the Dev Summit(s) and the UCs. They are short, focused and free to watch...something that you can do now, before a class.
Esri 2017 Developer Summit Tech Sessions - YouTube
or
E360 Video Search | Esri Videos search for "Web Appbuilder"