Dear Markwmsn,
Thank you for taking up my trouble. This is my first attempt to try to access and open my files, folders and disks in the external hard drive. Since I posted my question to this Support Community I came across MacUser Guide: Connect and use other storage devices with Mac, Move Files, to or from an External Storage device, and Get permission to view or work with files on storage device. I followed many instructions there. I’ve now successfully had my MacBook reached to a stage where Time Machine keeps ‘Applying Privilege to my Passport for Mac’. Time Machine has so far backed-up 64.4% during past 9 hours (my internet speed is slow.). I’d wait and see when it completed, whether I can access and open my files or not.
so please keep your fingers crossed for me. I will post my result to this Community. Thank you so much again.