invalid application password of gmail

Question

I tried to add an app password for my gmail following Google Gmail Help https://support.google.com/mail/answer/185833?hl=en&sjid=2565285338845314707-AP

Create & use app passwords Important: To create an app password, you need 2-Step Verification on your Google Account.

If you use 2-Step-Verification and get a "password incorrect" error when you sign in, you can try to use an app password.

1. Go to your Google Account.
2. Select Security.
3. Under "How you sign in to Google," select 2-Step Verification.
4. At the bottom of the page, select App passwords.
5. Enter a name that helps you remember where you’ll use the app password.
6. Select Generate.
7. To enter the app password, follow the instructions on your screen. The app password is the 16-character code that generates on your device.
8. Select Done.

I was told that 2-step verification is required for the app password to be effective. However, I received no 2-step verification after the app password has been done (point 8). I would appreciate it if someone could help me understand why 2-step verification was not prompted in my case. (Note: This app password is to be hardcoded using in our mass email sending python program. Here is the error after I have input the app password in the program : smtplib.SMTPAuthenticationError: (535, b'5.7.8 Username and Password not accepted. For more information, go to\n5.7.8 https://support.google.com/mail/?p=BadCredentials e28-20020a63545c000000b005cf5bf78b74sm2151276pgm.17 - gsmtp')

Thank you for all your help!

(Note: I expect the mass email can go through to the intended recipients without error.)