If you are planning on using shared cockpit, there is a little bit of configuration that is required. Whoever is planning on hosting, you will need to port forward the two selected ports in the Addon Manager. You will need to set an up to 8 digit password and click begin session. Configure your name, the IP you'll be connecting to, and the password in the connection options section. Once this is all done, enter the sim and click on the crew page, you can click on Pilot Flying or Pilot Not Flying to take on a pilot role. You can also just connect as an observer, but you will not be able to click anything other than the tablet.
If you are unable to connect, verify you have port forwarded. If you unable to connect after that, try using an exactly 8 character password. If none of this works, please open a ticket with us.