Postal Locations

I am puzzled and deeply upset over what happened today. About three weeks ago I fortunately caught a package by using the tracking system and traveling to the post office to retrieve it before it was returned to the sender. I was told because I didn't have a mailbox and therefore not in their database they could not deliver. I told them it was our cabin, however I was in the process of installing a mailbox because we have been spending more time at the "cabin" due to the virus situation. I was given the number to call when I had the box installed so my address would be added to the delivery data base. I called when it was installed and was told my address was added. Today I was to get a package per the tracking system. We had to leave for the day and when i returned I checked the mailbox (it was a small package) and it wasn't there. I searched the porch and rear deck and found nothing. I went to the tracking system and learned it was being returned to the sender. Since the office is now closed for the day, I hope I can retrieve it tomorrow morning and learn what went wrong in the delivery process. Whatever needs to be done to correct this from happening to others hopefully will happen.