The password described in the above document meets the conditions for automatic generation , but the password is not automatically generated.
("Require a password when scheduling new meetings"is enable and locked and “Require a passcode for meetings which have already been scheduled” is not checked)
The account license is at least professional.
Can you share the request body you’re using to create the meeting? This will help us to take a closer look. (Please leave out any personal info such as email, etc.)
As long as the passcode feature is enabled, your meetings will still generate a password. After enabling waiting room, disable the passcode setting and let us know if that helps.