Error on checkout page

Hey , I am currently facing a problem on my site
When i try to checkout using upi , it takes me to empty cart page and says cannot checkout while empty card but then when i check my user/orders and when i click on the option to pay , i am able to pay

The problem is that , i am not able to pay through the checkout page ,only the profile/orrders page
Please Help me

And Wonderful Plugin

The page I need help with: [log in to see the link]