Apple requires iCloud Users to use app-specific passwords for all third-party applications such as OnceHub. An app-specific password is a single-use password for your Apple ID that lets OnceHub securely access the information you store in your iCloud Calendar. This access method requires that you turn on Apple two-factor authentication or Apple two-step verification. 

In this article, you'll learn how to create an Apple app-specific password.

Creating an app-specific password

1. Sign in to your Apple ID account page.
2. Click Settings.
3. Under Apple ID, click Manage (Figure 1).
   Figure 1: Manage Apple ID
4. In the Security section, turn on Apple two-factor authentication if it is not on already. On older devices, use Apple two-step verification instead.
5. Under App-Specific Passwords, click Generate Password (Figure 2).
   Figure 2: Generate an app-specific password
6. Enter a password label (for example, "OnceHub").
7. Click Create.
8. Once the app-specific password is generated, copy it.

You can now use your new app-specific password to connect OnceHub to your iCloud Calendar.