If the Stream Deck app cannot communicate with the Ecamm app, you may see the message Open Ecamm or Open Ecamm Live in the set-up screen.
Ecamm's Stream Deck plugin communicates with the Ecamm app via a local network connection. This error typically indicates the plugin cannot connect to the Ecamm app for some reason.
The most common reason for this is an issue with macOS security settings. To check on this, open the Mac's System Settings app, and go to the Privacy & Security pane. Scroll down to find the section called Local Network.
Ensure that permission is granted by enabling the toggle next to Ecamm. Also be sure to grant this permission for Elgato Stream Deck if you see the option there.
More Troubleshooting Steps
Multiple Instances of Ecamm
You may see multiple instances of Ecamm.app listed in the Local Network security settings. This happens when there is more than one copy of the Ecamm app on the Mac, and can cause issues with the macOS security settings.
To fix this, search for and delete any extra copies of Ecamm that you may have on your Mac. Ensure that there is only one, and that it is in your Mac's Applications folder. Once you have done this, reboot the Mac.
Run Ecamm from the Applications Folder
Ensure that you are running Ecamm from the Applications folder rather than your Downloads folder or some other location. To check on this, open Ecamm, and then right-click or control-click on the Ecamm icon in your Mac's Dock. Pick Options → Show In Finder. Ensure that the app is in the Applications folder.
Third-Party Security and Firewall Apps
Local network connections is communication between apps on your Mac. Certain third-party firewall and network security tools can prevent local network connections. Ensure that you are not running a tool that does this. If you are, ensure that the tool is not preventing local connections.