Repair PayPal Buy Now Integration

My WordPress site (built with the free version of Elementor) has a Buy Now PayPal button on the payments page—see the very bottom of https://simplystenovoice.com/payments/. Since the recent rebuild the button still displays, yet it throws error messages once a customer tries to pay... (Budget: $20 - $60 USD, Jobs: CSS, Elementor, HTML, JavaScript, Payment Gateway Integration, PayPal, PHP, WordPress)