You will need your Reseller API credentials from My Account -> API Settings in the Netistrar OTE Dashboard. These are found under the REST API section as shown below.
Once you have completed installation you will need to log into your WHMCS installation as an administrator and visit /admin/configregistrars.php. If the installation has been successful you should see the Netistrar module within the list as shown below:
Click activate and if successful the panel will automatically expand with configuration as shown below:
Ensure that the OTE is selected (we strongly recommend substantial testing in OTE before using production credentials) and supply the API key and secret as obtained above. Once completed click Save Changes.