Paypal integration with Woc

[hoshina235]

I setup my Paypal with Woocommerce, but whenever I try to simulate a real purchase I get the following error 

Video reproducing the issue > https://drive.google.com/file/d/1C4N9vYbRMZRCkmjT7mYbqu_-Bsvox6rN/view?usp=sharing

I've done  second test with Sandbox enabled. At first it seems to work, but when I go to Wordpress > orders, all transactions appears as pending and then cancelled.

Thanks!