How to purchase 4 copies of Turbo tax download not CD for my children who live in different states as presents??

In the past, I have bought CD Turbo Tax copies for my four adult children as Christmas presents and you mailed them to my home address.  This year, they all requested down load copies and not CD's.  So, how do I do this?  They all appreciate getting this present.  Three use Mac and one uses Windows copies.

Thanks