Hylandgreen is right.

From HPD website you posted above:
"There is a 14 day waiting period on all permits. After the 14-day waiting period the permit will be valid for only 6 calendar days. Permits not picked up by the 6th day will be voided. Applicants will need to reapply and go through another 14-day waiting period, so please plan accordingly."
This applies to both rifle and pistol permits.
Although the longun permit is valid for a year after picked up, you only have 6 calendar days to pick it up after the 14 day waiting period or you start all over.
That's why they post pick up dates on the window when you apply.
Also from HPD :
"As an option, applicants may have their processed permits mailed to them. Applicants need to provide a self-addressed, certified restricted-delivery, pre-paid envelope (available at the U.S. Post Office) when coming for their initial application for permit. Long-gun (rifles/shotguns) permits are valid for one (1) year from the date of issue. Be advised that a handgun (pistols/revolvers) permit is valid for only ten (10) days from the date of issue.
Reference:
HRS 134-2: Permit to acquire"