I stopped Portainer and setup your add-on. for me the steps were simple. Only CUPS (for printing) was running in portainer. If you could setup cups as add-on too it will solve it printing issue for many people.
copy sharing key from FR24 data sharing site (using laptop not available on mobile app) and paste in configuration.
Add my location latitude and longitude with 6 decimal places.
It is working partially one issue
2021-10-12 21:50:46 | [mlat][i]Stats 24/0
2021-10-12 21:50:49 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:50:59 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:51:06 | [feed][n]ping 2
2021-10-12 21:51:06 | [mlat][i]Pinging the server
2021-10-12 21:51:07 | [mlat][i]Stats 24/0
2021-10-12 21:51:07 | [feed][n]syncing stream result: 1
2021-10-12 21:51:09 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:51:19 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:51:26 | [mlat][i]Pinging the server
2021-10-12 21:51:26 | [mlat][i]Stats 24/0
2021-10-12 21:51:29 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:51:36 | [feed][n]ping 3
2021-10-12 21:51:37 | [feed][n]syncing stream result: 1
2021-10-12 21:51:39 | [mlat][i]No ADS-B time reference available (0/0)
2021-10-12 21:51:46 | [mlat][i]Pinging the server
2021-10-12 21:51:46 | [mlat][i]Stats 24/0
2021-10-12 21:51:49 | [mlat][i]No ADS-B time reference available (0/0)
Edit: cups docker container can be found here Setting up local USB printer with CUPS via Portainer