Whne you click on Netdocuments within ACtionstep and you get the following screen stating

"Requests to the server have been blocked by an extension"

This issue is because you need to have NetDocuments open and logged in on another tab within your browser.

Currently, this is a known issue with Actionstep and only affects client who are using Single Sign-on  (Federated Identity) with NetDocuments (ie log in automatically to NetDocuments without password) and currently the above suggestion is the only workaround.