These requirements are in addition to the WHMCS default system requirements
- Valid active eNom account
- WHMCS Server IP whitelisted with eNom - Details can be found here https://help.enom.com/hc/en-us/articles/115000104711-How-to-Whitelist-your-IP-Address-for-API-Access
- USD set up as a currency within WHMCS
- The PHP directive 'allow_url_fopen' set to 'on'
- If using Wordfence - The PHP directive 'auto_prepend_file' set to "" (no value) for the WHMCS folder