I have problems, when I press the paypal button it does not connect the popup with paypal.
Yes, you have a bug. If you want actionable feedback, I recommend sharing a lot more about your set-up. Perhaps show screenshots of the workflows and actions, the API parameters, etc. Then, perhaps someone will be able to spot the bug.
Hi,thanks for your time,
In merchant ID, public key and private key, everything is correct, copy and paste, my account is sandbox, and my workflow is this 
I do not understand the problem.