Our group loved Silvia's apartment! I personally loved the aesthetic and way she curated her place. Lots of cool vintage details and there was always something new to notice in her trinkets. The space was great and had everything we needed. Silvia did her best to accommodate when my group asked if we could drop off our bags before check in. I'm sure it's dependent situation by situation, but it definitely helped my group out a lot. There were times in which I needed to communicate with Silvia and needed to wait a bit. In the end, she responded with the information our group needed!
There was one set of keys for the apartment for my group to share, which ended up being fine. Depending on the needs of your group, just know access isn't with a door code.
Wish my group's agenda could have included more time to explore Madrid because we certainly felt like we could have enjoyed more time in Silvia's place as well!