UnSuccessful Payments

I have been trying to build an app for a year now. I would least it and hope the issues fix sooner or later. I am now returning to see if I can have a successful payment go through and it just wouldn’t. I am not sure why. I get a message saying please retry or something along those lines. I know it is not my website as payments go through on the website. This thing is so difficult and not promising for a store.