p means print the partition table. So currently you have no partition set on sdb.
The tuto says for a gpt partition:
Then if you ask again a p after saving (y) you will see a new partition (8 <=> sdb8)gdisk /dev/sdb
The commands to be given are:
x
l
4096
m
n
8
5804032 (start sector)
(enter) (end sector)
8300
w
y