You don't need to reimport the wallet.dat on the GUI since you already placed the wallet.dat file on the wallet directory which is "C:\Users\Admin\AppData\Roaming\Bitcoin"

Look you already opened the Bitcoin core GUI it should show some error if the wallet.dat on the wallet directory is corrupted.
That is why this error come up because you are attempting to reimport the wallet.dat that is already in the wallet directory.