Adding a user to my account


I would like to add a freelancer to my account who will be using some of your assets to produce work for us, he is in florida, I am normally based in London (though in turkey at the moment). Each time he tries to access the login details I give him he is blocked down to IP address most likely, and so I reset and send him a link which inevitably expires before he gets to it. Whats the best way to resolve this problem as he will be doing quite a bit of work for us and I would like the record of assets purchased to be within this account.