First of all, I would remind the place that the check-in time of 15:30 is not ok. Especially when you literally cannot enter the place to leave your luggage and freely walk around, or just wait for the last hour inside.
15:30 — really? This is the time not to punish or humiliate the guest, but to prepare the place for a new guest. 4 and a half hours to prepare the bed?
Ok, maybe Green Hostel Oviedo uses this time to make it impeccable clean — also no. When I was introduced to our "Private bathroom", I was shocked, not even from the conditions, but that the person at reception was not ashamed to show it to me in such conditions! It was a bus station bathroom. Why? Because it is not "private" — it is a bathroom in a corridor next to the kitchen, and literally everyone uses it when needed. It's private only by a note on a door which no one reads.
Breakfast is as basic as it can be — no eggs, butter, just dry stuff, bananas and apples, which went bad in some places. One morning, the coffee tank was not refilled, so the people had to incline it to get at least something. So they used plates for coffee.
Yes, this is a hostel, but it is not a favour, we pay for it. And praising the fantastic location in the city of Oviedo size, just let's not forget to respect ourselves.