this is automatically set up in the plugin for you, you don't need to do it.

you're not getting redirected?

are you in a localhost environment or similar?

Hi - after an hour on the phone with Authorize.net support we figured out the problem was actually CHROME , works fine in other browsers. So I will just put a message not to use Chrome until the next Chrome update and check again. Thought you would want to know

Thank you for prompt reply