If you're not seeing the "USB-Serial Controller" entry when trying to use a serial connection on a mac. You probably need the missing driver:

Open the "App Store" and search for "Prolific".
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You should find an app called PL2303 Serial.

Click the "install" button.

Click "Open System Settings"
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It will tell you installation was "blocked", click "Allow" and confirm with password or fingerprint.
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Now try connecting the monitor again, this time you should see it listed:
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