What kind of base is required for this mailbox post?

This is from the manufacturer's website for 5106 post: For a new concrete pad, pour the concrete in your desired form and insert j-bolts into the wet concrete in the correct 4” x 10” bolt pattern. Allow concrete to set before attaching the post. For an existing concrete pad, install concrete anchors in the correct 4” x 10” bolt pattern and attach the post to the anchors.

quick setting concrete or regular quikrete.