This is how you get the Infusinosoft API Credentials
http://ug.infusionsoft.com/article/AA-00442/0/Infusionsoft-API-Key.html
Step 1:
Login to infusionsoft: http://signin.infusionsoft.com
Step 2:
Go into Admin -> Settings
Then select “Application” on the left hand side.
Under here will be the API Key.
Step 3:
Grab the front end of your url.
Now put those values into the plugin.