HI,
If you go to your reservations page, you see a column called "details". Click on one of the "View VAT invoices" to open it. On top of the invoice you find the address + VAT number. Don't know if this the same for Portugal, but in my country The Netherlands it says:
Airbnb Ireland UC, The Watermarque Building
South Lotts Road, Ringsend, Dublin 4
Airbnb Ireland VAT ID: 9827384L
Added:
I found out every AIRBNB website has an "about" page, for Portugal it is:
It shows the same addres as mentioned above for your country.
Best regards,
Emiel