To create a rank, it needs to be underneath the configuration section prisonpick.rank.
# The autosell.yml file defines what blocks sell for what prices.
#
# Since most prison servers function by groups and ranks, different permissions can have different prices
#
# Instead of depending on multiple permission plugins, PrisonPick looks at the permissions of a player instead.
#
# For example, if a player has the permission prisonpick.rank.a and that permission has DIAMOND_BLOCK
# for 50 (type of currency), then the player will be given 50 of the configured currency.
#
# These permissions must be in the format `prisonpick.rank.{GROUP}`
#
# If a player has more than one of the following permissions, and a certain item is found in both,
# the player will be sold the higher priced item.
prisonpick.rank:
a:
DIAMOND_BLOCK: 500
EMERALD_BLOCK: 750
b:
DIAMOND_BLOCK: 750
EMERALD_BLOCK: 1000