Re: "Can’t access locked files on icloud web" (due to message): “Cannot View Note.This note uses a locking method supported only in Notes for iOS, iPadOS and macos. To view locked notes in Notes for iCloud.com, switch to using a custom password on one of those devices."
If I understand correctly: the way you locked Notes limits the access to the iPhone: Seems you need to:
change the locking method in use in the Notes app, to a password you can use in iCloud.
Eg: See Apple support's article (link below) for tips:
How to lock or unlock notes on your iPhone or iPad - Apple Support
Eg: says:
"Switch from your notes password to your iPhone passcode
- Make sure that iCloud Keychain is on. To use your device passcode for locked notes, you must turn on iCloud Keychain.
- In the Settings app, tap Apps, then tap Notes.
- Tap Password.
- Select Use Device Passcode.
- Use Face ID or Touch ID, or enter your previous notes password.
- Enter your iPhone passcode.
- Tap OK. All your locked notes that used your most recent notes password are now updated to use your device passcode.
If you choose to use your device passcode to lock notes but later remove your passcode from the device, you can still access the notes you locked with your passcode."
