The Guidelines are missing all of the info! I did a couple last week and chatted with the MSC to confirm the following:
1. You can pick any of the scenarios listed.
2. You can ship to any zone, just needs to be to a different zip code than the one you are mailing from (without the Zone requirement it make this whole shop sort of pointless, but what do I know?!)
3. If they deny Priority, you ship Ground Advantage - this is for all scenarios. Not sure how you could end up in a situation where you need to buy stamps, but with the cheapness of this MSC I wouldn't advise buying anything as they are unlikely to reimburse it.
So I personally just used the easiest scenario "Mailing a laptop battery" since that would need to be shipped Ground under all scenarios/distances and both were accepted right away.