Enter this verification code in the chrome extension to enable iCloud passwords

On many websites recently a little window pops up in the lower-right-hand corner of the screen. It says:

Enable iCloud Passwords extension for Chrome

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Enter this verification code in the chrome extension to enable iCloud passwords.

But there is nowhere to enter a code. When I go to the Extensions section of More Tools in Chrome it also provides nowhere for a code.

This happens on websites with passwords. The user name and password are already filled in and there's no place to enter a code. If I've entered the password, the message seems to randomly pop up on other pages in the website.

I'm using Windows 10 on an i7 laptop with 16 GB RAM and a 1TB SSD.

Please advise.