The only time I've tried to use Verizons Store to upgrade my phone, and the website is FUBARed. Not even sure if my order went through. Got all the way to Paypal checkout only for it to kick me out to the empty cart screen. Now it says I've maxed out the amount of devices I can have or that my account is invalid OR that once in a while message that says they are trying to fix an issue.
My favorite is when it just kicks me to a HTML error page, clearly written in java but not working.
1) Verizon is iffy with Paypal. I tried before on a $0.00 order because I didn't feel like typing in a debit card number and it held it for "fraud". Had to call up to get the order unfrozen and that was super annoying. At that time, Verizon didn't charge an upgrade fee if you did a device payment over a 2 year contract.
2) Don't buy phones from Verizon. After a seperate incident related to the same phone involving the app taking my buyout for the phone and applying it to the bill instead despite email confirmations I was upgrade eligible again, I just went with unlocked phones.
Getting a new phone is always an exciting time! Have you tried clearing your browsers cached data before attempting the order?