Google Analytics (track email opt-ins through to Clickbank sales)

I need a Google Analytics expert to help me track sales of Clickbank products. This will involve cross-domain tracking. Here is the flow of my online sales process: 1) A visitor comes to website #1 2) While they are on website #1, a pop-up asks them to enter their email address (I use OptiMonk to capture email addresses). 3) When the visitor enters their email address into the OptiMonk form, their email address is automatically stored in my Optimonk account AND in my autoresponder account (ActiveCampaign). 4) Once the email address is stored in ActiveCampaign, an autoresponder sequence is started, sending out regular emails encouraging subscribers to visit website #2, website #3, and website #4. On each of those websites I sell one Clickbank info product (so, three products in total). 5) Some people purchase my Clickbank products from website #2, website #3, and website #4. ** I need someone to set up my Google Analytics so I can tell which Clickbank sales are being made via the autoresponder sequence.** So my goal is to know which Clickbank sales my autoresponder sequence is responsible for. All of my websites are built on Wordpress. I need someone to set up this tracking for me, and explain to me what they are doing. When bidding on this project, you MUST briefly describe your experience in doing this type of set-up for other clients. I will delete bids that do not include a brief description of experience doing similar set-ups.