To get started with WHMCS you'll first need to choose WHMCS as a trigger or action when creating a new zap.
When the time is right you will be prompted to connect a WHMCS account.
You'll be prompted to enter your WHMCS host and API key.
The host should be your fully qualified domain name without any extra slash at the end. For example "https://whmcs.example.com" (without the quotes). You will need to enter the username and password for an administrative user, which we recommend creating a separate API user so you can better track activity.
Unfortunately due to the more dynamic nature of our backend servers it's not possible to allowlist IPs for API access so you will need to generate an API key. WHCMS' documentation outlines how to accomplish this, once you have followed those steps you can then add it to the authentication dialog on Zapier to continue.
If all is done correctly you should see the authentication added successfully as follows.