I successfully restored all my volume data to another USB disk (all-at-once option). When I plug this USB to another PC, Windows pops up 'Access denied' error and my data not accessible. Why this happens and what to do?

Most likely this is a Windows security issue, so this recovered volume has been created under Windows user account that has not been registered (or doesn't have enough rights) at the PC where you plugged in your USB. You need to log on as an Administrator and assign proper rights for the volume to be accessed.

Here is a video how you can do it.