Log in to your CRM then click the icon in the top right corner. It is recommended you create an API user rather than using an individuals account.
In the menu that opens click "My Account"
A new window will pop up. Click on "API Keys"
In the page that opens click on the + sign.
In the Description put anything you wish and click the save icon.
Copy down the information generated you will need this for the module.
In the Admin page click "Settings" > "CRM Settings"
For CRM Type choose Connectwise and click submit.
The connectwise API does not return an appropriate error if you choose the wrong server. If your user cache doesn't update check your server.
You can set a custom URL for self hosted instances by going to Advanced Settings and looking for "Custom CRM url".