Hi hnikitop,
If we understand correctly, you're looking to generate an app-specific password for a third-party app. Is that correct? If so, we'd like to share a link that has the specific steps you'll need: Sign in to apps with your Apple ID using app-specific passwords
"Some apps made by developers other than Apple ask you to sign in with your Apple ID, so that the app can access information like mail, contacts, and calendars that you store in iCloud. To help make sure that your Apple ID password can't be stored or collected by the app, you can choose to create an Apple ID password to use only with that app."
"How to generate an app-specific password
- Sign in to appleid.apple.com.
- In the Sign-In and Security section, select App-Specific Passwords.
- Select Generate an app-specific password or select the Add button
, then follow the steps on your screen. - Enter or paste the app-specific password into the password field of the app."
That should help you generate a password for your app. Let us know if you have any questions, and take care.