Hart van Zeeland is located near Hof van Zeeland, but the two are unrelated. If you are staying at Hart van Zeeland, you do not need to report to the reception at Hof van Zeeland.
Hart van Zeeland accommodations use a digital lock. This FAQ explains how to open the door using your smartphone.
Accommodation B108 is an exception; it is accessed using a key from a key safe. The check-in email will tell you which key applies to your stay.