I am already signed in to the system, still username and password are asked during training/validation split data file download.
What are those credentials for me? I tried using my account credential but that does seem to be working.
1) to download the data, you first need to register on the Chalearn webpage (this will require you to define a username and password).
2) then, after having the data downloaded, you can use the decompression keys provided on Codalab page, Participate tab.
I hope this answers your question.