To verify if Keychain is enabled on your iOS device:
1. On your iPhone, iPad, or iPod Touch, go to Settings.
2. Click the first section, which contains your name, profile picture, and "Apple ID, iCloud+,...".
3. Locate and open the iCloud section.
4. In the APPS USING ICLOUD list, verify if Passwords and Keychain is ON or OFF. If it' ON?, then Keychain is enabled. If not, open the section and enable Passwords and Keychain by checking on the toggle.
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