Restore WhatsApp from backup without password

After re-installing the app,  I’m trying to restore my WhatsApp via an iCloud backup but I don't know my password and do not have an Encryption Key

Is the password my iCloud password or was I asked to create a new/different password via WhatsApp? 

I have tried my iCloud password (I reset this and tried again) but it is not working. I've tried a few likely combinations but I now get locked out after each new attempt (currently waiting 7 hours to retry).

The advice on the website "Tap Chats > Chat Backup > End-to-end encrypted backup > Change Password." also does not work as that option isn't given to me as I don’t want to turn encryption on and create a new backup. 

How can I reset the password and restore my chat backups? 

iPhone / Chrome 114.0.5735.124