So nice to see a fellow Pittsburgher on Shopify!
I think I can help you on this one. You might need to set up a third party checkout to inigrate Tap. Do you have a merchant service provider to assist on this? It can get a little bit funky making all the parts work with Shopify.
Incom Direct, the company I work for, has worked with other Shopify users. We offer 24/7 tech support and do not have 1-800 numbers--you call and get to talk to a human.
Our rates are extremely competitive. Send me an email at AgentSupport@Incom-Direct.com, my name is Margaret.