When trying to connect an Arduino Uno Wifi Rev2 through the Web Editor on a Chromebook. When trying to connect to a port the only option is /dev/ttyACMO . When completing the same procedures on a PC we can select a com port and Upload a sketch. When trying to Upload the same sketch on a Chromebook it starts uploading but errors out when flashing.
Nobody will be able to help you if you don't provide the full error message. It's just a suggestion, I have no experience with chromebooks nor with the Uno WiFi Rev2 so can't help further.
I think Chromebook (ChromeOS) is Linux base, and security based (denying access to attackers). You are probably logged in at "user" level. See if you have an administrator level command (like "sudo") to allow your user session to use comm ports.