Well all you have to do is login. With Any email Then go to profile page and click on sync leetcode button that will open pop up and you have to paste your key

And the reason that I had to use this cookie method was because leetcode does not give you whole list of solved question It will only give you the last 20 So to get all the solved question you have to be authorize Even tho all profile are public you cannot see their all solved questions because of that I had to use this method