When selecting which channel/product to link to Chat 2 Pay in the Clickatell Portal, only those channels/products that you have activated on your account will be available to select.
If you cannot see the channel/product you want to link, it means you first need to activate this channel/product on your account. Once activated, they should be available in the drop-down when selecting what to link to Chat 2 Pay.
See here for the steps to do this:
SMS and two-way channels, automation, call center integration, payments – do it all with Clickatell’s Chat Commerce platform.