Check these; hopefully they get things sorted out:
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Make sure you have registered your chromecast device on the developer console. Double check the serial number since sometimes it is hard to read it.
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During the chromecast setup, there was a box stating something like “Send the serial number ..”, make sure that is checked
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Wait 1/2 hour or so and reboot your chromecast
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Check whether you can access
http://<chromecast-ip>:9222
from a chrome browser on the same wifi network; if you can, then your device is ready for development
As for the area on the image that you have pointed to, that is more for informational purposes at this point