NOTE: My friends and I rented the AirBnB for our stay during the Primavera Sound festival.
The airport transfer went really smoothly and was super convenient and reasonably priced. There were 8 of us and it was 60 euros!
We got to the apartment and the street doors were already open and the guy that met us "explained" the virtual key. He had me follow the link and hit the button and a green check-mark popped up indicating that would open the door (if it were not already open). This was NOT a full explanation of what was needed to actually get the door open and was missing an important step. We found this out when arriving home after going out in the city (like 3AM) and not being able to get into the apartment and having to wait for someone to exit the building to get in. We told the check-in over WhatsApp and they gave us the added step the next day.
The other issue with the virtual key was that the power in the building/apartment kept going out so it would render it useless. When we checked in they gave is one physical key (for an airbnb with 12 beds) but said we would "never have to use it because the virtual key always works." The power went out 3 of the nights of our stay so we again had to wait for people to exit the building to enter. There isn't actually a keyhole in the door to the apartment but the backup way of getting in was never explained to us (until we were again locked out late at night after coming home).
I sent multiple messages about the power/virtual key issue as well as an issue we were having with one of the toilets and got no response to them (and could tell they'd been read on WhatsApp).
The apartment and location were great don't get me wrong but the system in place for getting into it it very unsafe especially for those planning on staying out late in the city.
We also got a noise complaint almost immediately despite it being before "quiet hours" which was kind of disappointing because we then had to plan to go to our friends airbnb the entire weekend instead of being able to use our own.