Migrating/Connecting Third-Party Payment onto New Webflow Site

Good Morning,

I am working on a new website for a client. They have a tab where the customer can “Pay Invoice Here”. The third party extension is First Data Corp - Merchant Services | Payment Processing Enterprise Solutions | Fiserv

It looks like they actually have plugins when I checked into the website. I am migrating from WordPress to Webflow - could anyone give some insight or best practices on how to migrate this to the Webflow site? I know the SSL Certificate will need to be updated?

Client’s current website - https://checkout.globalgatewaye4.firstdata.com/pay

New website live link (The Pay an Invoice tab has not been updated yet)
LIVE LINK: https://signworks-memphis-1.webflow.io/

Thank you!