Gain access to old drive folders

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Hi all,
I've just built my first new rig in 10 years. All went well and system stable. Been reinstalling everything on new NVMe Drive. I'm keeping my old Samsung SSD 2.5" as a usuable drive once I've got everything off it.
But I'm stuggling to gain access to certain folders. My Documents being one of them. I need Read access apparently and the instructions really don't help.
Anyone got any ideas how to achieve this please?
TIA

 

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Update on this. There are just two folders on my Old OS Install Drive that I can't access now. My Documents and Desktop folder.
Its just beyond me how to do it. I know its possible but how