Hi Subha,
You are not quite doing this correctly. You are copying from one foot and pasting to the same foot.
In Blender 2.8+ there is no button in the UI to do what I’m doing in the recorded lesson, but you can achieve the same result with the keyboard shortcut (or the menu option)
Here is the key thing that you are missing.
You want to copy the POSE in the VIEWPORT. (hover the mouse over the 3d viewport, make sure the Foot_IK.L is selected then press CTRL C.
And then you want to paste it to the other foot using the Paste Mirrored in the VIEWPORT. With the same foot selected press CTRL SHIFT V, and this will paste the mirrored version to the .R side (even though you still have the .L selected)
Hope that helps.
