This is fairly common. Sometimes, the postal service might mark your package as delivered 3-4 working days before it is actually delivered. Please give it a few more days for it to arrive!
Please also check with other members of your household and your neighbors, and your usual mail delivery spots.
If you still don't have it after 5 working days after your package is marked as delivered, please contact us at firstname.lastname@example.org
Please write to us at email@example.com and we'll help you out!