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 but it's not and you are still able to go to File > Restore Wallet.
That is why this error comes up because you are attempting to reimport the wallet.dat that is already in the wallet directory.
Thanks for your reply.
In the event I want to import an old wallet.dat and see transaction history from possibly 2013.
Do I need to download the entire blockchain?
This is how I installed Bitcoin Core yesterday, and I think I did it incorrectly.
https://imgur.com/afzKvBmI think the mistake is, I had the "Limit block chain storage" ticked.
Please let me know, thankyou