steam account/new laptop wont let me download any items from purchase history

hiya I recently changed laptop and have downloaded my steam/sims account onto it.
I can play the game no problem. but I cant download all my previously purchased items.
I go to store> my store account> purchase history.
it shows me all my items (clothes, buy/built objects, world, broadwalk set, roaring heights) so a fair bit of money has been spent!

I click on the select/tick box of an item then click download. a little box opens saying 'best done on a browser, make sure sims game isn't running' etc etc. I click 'download'  then a new tab opens.... but its completely blank. nothing happens and that's it. help!!! getting annoyed now.

ive tried using chrome, firefox, internet explorer. same thing happens. I only downloaded it all a few days ago so it should be up to date.

thankyou in advance!!!!