Thanks @tpriyan and @FrilledShark I got it taken care of. I was assuming they want the public key to send Burst to, but in fact they wanted the account ID BURST-XXXX-XXXX-XXXX. Its all good now.
You guys have a magnificent day on purpose!
You can buy 1000 Burst on three exchanges now:
A short description of each:
Or you can trade with a user here on the forum of course.