At the airport
Carrying for someone is normal and allowed. Airlines just expect you to say so.
If you're asked, say yes
Check-in and security ask whether anyone gave you something to carry. On a Pasabay delivery the answer is yes. Answering no is a false statement to aviation security.
Keep it where you can reach it
Pack the item so you can take it out without unpacking everything, and keep it with you from handoff to delivery.
Have the record ready
Open the delivery in the app: who handed it over, what's inside, and the handoff photos you both confirmed.
Check your travel insurance
Most policies exclude carrying goods for a reward. Check yours before you agree to carry.