Assign required permissions to developer on Workday

Here's the thing, I tried to create a community account on Workday, but I never got back any email from them in order for me to ask my question there, so probably SO community will be helpful.

I want to develop widgets that would pull information from Workday. I want to know what is required from the Workday environment for me to be able to develop these widgets.

These widgets for example, will show information about the current user, for example the number of days of vacation left, etc.. So I want to use Workday REST APIs. Now the question is, since I don't currently have access to a workday environment, I'm not sure what to ask the client for. What permissions should they provide me #1 as a developer, #2 as a service account that will be used later to run these calls.

Any help and guidance from someone who has done similar thing would be really helpful.