ASA 5505 running ASAos 9.1.2
CentOS 7

Configure the ASA:
en
conf t
policy-map global_policy
class class-default
flow-export event-type all destination 10.10.10.150
flow-export destination management 10.10.10.150 2055

NOTE: I'm using port 2055 as the flow destination on the ASA (10.10.10.150 being the host running ntopng).

Install ntopng and redis (follow these steps):
https://devops.profitbricks.com/tutorials/install-ntopng-network-traffi…
Configuration file needed a tweak (original file only had the first line, which needed to be modified):
# cat /etc/ntopng/ntopng.conf
-G=/var/run/ntopng.pid\
--community
tcp://127.0.0.1:5556

Installed nProbe
yum install nprobe
systemctl enable nprobe.service

Startup sequence matters.... so start nProbe, then ntopng

nprobe --zmq "tcp://*:5556" --collector-port 2055 -n none

systemctl start ntopng -l
systemctl status ntopng -l

You should now be able to browse to the web portal:
http://10.10.10.150:3000/

Hopefully that's it.