Error when using the "try it now" for rest apis

Hi,

I am currently creating an application and one of the requirements from our users is to be able to electronically sign documents.

Looking at your website (How to Send an Agreement through REST- API (Tranisent document ) | Adobe Sign ) I found a page with a "try it now" capability. When I tried to use it it fails with the following message:

{"code":"INVALID_API_ACCESS_POINT","message":"Request must be made to correct API access point (e.g. use GET /base_uris)."}

Can anyone assist as to what the error means or correct me if I am doing something wrong?

Thanks