I can enter my account and add some products in my cart ,but can't take them from the market. Its write "Magento Marketplace Customer Agreement". When i click "I agree" its don't happen nothing, its not let me go forward.
Try using a different browser (if you used Chrome, try Firefox) and clean browser cache before you load the page. Some account features on Magento website did not work for me in Chrome but worked in Firefox.
hope this helps.