Is the GSP involved?
At any rate FIRST correct your Paypal address.
Then contact the seller and if he has not yet shipped, he can correct the address manually.
If he has shipped, hmmm.
Apartment building? Put a big Note on your box for the postie that you are expecting a parcel and this is where the delivery notice should go.
If the supervisor or concierge normally collects tenants parcels, there shouldn't be a problem, but let her know that you are expecting this one in particular.
Commercial or Industrial building? Is the company name on the parcel? Does Reception usually accept parcels? Talk to her about it.
You should also talk to the Post OFFICE (not outlet) where your postie sorts his bag. A message there would also be helpful.
The bottom line is communication.
If the parcel is undeliverable, it will eventually be returned to your seller.