Paypal button code not letting buyer login and pay

I am having some issues getting the custom paypal code injection to work completely on a website I am working on for a client. The code injection works until I try to test it and it wont let me sign into paypal when the dialog box appears. I know my username and password is correct, and I've even used another paypal account to login and that doesnt work either. I attached screenshots of what happens when I try to pay for a service. My squarespace is connected to paypal but I not using the checkout feature. I also have a business account. If anyone has any tips or knows what to do it would be greatly appreciated! Thank you!