Please excuse a beginner question. I'm trying to integrate PayPal standard checkout with my new web site. If I follow the instructions found on the developer pages, using app.js and server.js (along with a few other files) in a stand-alone test, it works just fine. But when I try to integrate with the rest of my site (without using npm), I get a 403 Not Found error, followed by an error saying it gets an unrecognized token of '<'. Can somebody please point me in the right direction? Thanks.
P.S. I recognize that the '<' token is coming from html, rather than a JSON string (in fact, it's coming from <!DOCTYPE...>), but don't know why. I'm hoping that solving the Not Found problem fixes the second problem.
