Passwords won't sync from MacBook Pro via iCloud to old iPad

I was given an old iPad running iOS 12.5.7. It's logged into my Apple ID. It was purchased at an auction and was fully factory reset.

I already have a 16-inch MacBook Pro from 2019 running macOS 14.4.1, also signed in with the same Apple ID.

AutoFill Passwords is enabled, but the passwords aren't syncing between the devices. This means passwords are automatically filled on my MacBook Pro but not on the iPad.

What am I doing wrong?

Here's what I've tried so far:

• iCloud Keychain Settings: I double-checked that iCloud Keychain is enabled on both the iPad and MacBook Pro. Here's how to find it:
  • iPad: Settings > Your Name > iCloud > Passwords & Keychain
  • Mac: Apple menu  > System Settings (or System Preferences) > Click your name (or Apple ID) > iCloud.
• Apple ID Consistency: I verified that both devices are logged into the same Apple ID. You might be signed in with different Apple IDs on each device.
• Restart and Updates: I restarted both the iPad and MacBook Pro to see if that would resolve the syncing issue.