Hi Ved D,
The Master Password for the backup is set to be the same as you used on the original device that you first synchronized (back in 2016). I'm afraid that the Master Password cannot be reset or retrieved. This is a security measure to prevent any unauthorized access; because this one password protects all other passwords that you have saved, it is critical that it is not compromised. Any passwords you have saved in the cloud for this synchronization group are encrypted with this password, and I'm afraid that if you have lost or forgotten the Master Password then those passwords cannot be decrypted and are no longer accessible.
If you cannot recall the Master Password you used on your first synchronized device, I can arrange for the currently synchronized data to be deleted. This means that the passwords saved in the cloud will be gone, but you will be able to setup the synchronization on your devices again as if you were a new user. If you wish this to be done, please confirm that you are aware that you will lose access to any passwords saved in the cloud, and that you authorize me to delete the data.