Hello @Giorgio204,
Yes, when you're due a refund and have a PayPal account you should get it within 24 hours.
The article below lists times for different types of accounts.
https://www.airbnb.ie/help/article/1967/when-will-i-get-my-refund
As it's now long overdue wyou should contact Airbnb support to discuss the issue.
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.