Everything was great, as far as facilities go. Perfect location for old town, port, restaurants, bars, etc. Very enjoyable experience. Cartagen̈a is great.
To check in, however, there's a small, sliding-glass door to the office, to the right of the actual apartments where you have to check in. Staff was friendly and helpful.
If you're driving, it takes a bit of work. I parked nearly directly in front of the apartment into a "yellow" parking zone. The staff will give you a discounted parking card that will let you in and out of the garage whenever you want by pressing it onto the gate's scanner. It's technically illegal to park out in front, but if you hurry, my experience with Spanish police is they're very forgiving as long as your flashers are on, someone else is in the car, and you're there checking in. Look on Google maps or earth to get a feel of the street. The garage is next to the building where the apartment is located.
Get to Cala Cortina beach by 11am or so to get a parking spot: restaurant, toilets, beautiful setting. Small, round pebbles, no sand, which keeps your body and stuff clean. Enjoy.
My wife & I were very impressed with this property, ideally located, plenty large enough for 4 adults or a family, comfortable beds & accommodation, excellent facilities all round. Car park was next door albeit very tight.