This knowledge base article requires you to have already setup the WHMCS Reseller Module
Reseller SSL Setup Instructions
How to add a Reseller Sectigo Domain SSL
Within your WHMCS Admin, Browse to Products/Services > Products/Services
Click the Create a New Group button
On the Create Group page provide a new Product Group Name, ie SSL Certificates
Click Save Changes
Browse back to Products/Services > Products/Services
Click Create a New Product
On the Create a New Product Page
Product Type : Other
Product Group : SSL Certificate
Product Name : Sectigo Domain SSL
Module : AbsoluteHostingReseller
Create as Hidden : On
Click Continue
On the Edit Product Page, click the Pricing tab and change Payment Type to Recurring
Set the Annually price, ie 160.00
On the Module Settings tab
Module Name : AbsoluteHostingReseller
Server Group : Absolute Hosting
API Username : Paste API Email Address from the Reseller Area Page
API Key : Paste API Key from the Reseller Area Page
API Endpoint : Paste API URL from the Reseller Area Page
Set Automatically setup the product as soon as the first payment is received
Click Save Changes and wait for the page to reload
Product : Sectigo Domain SSL
Click Save Changes