As per image below and number 16N619 your vehicle should have provisions for one. How ever if memory serves me correct back then it was an option to have it fitted when the vehicle was first purchased. In saying that the part you need is 4M5J 19G244 AA from Ford and around $35-40.
https://www.ebay.com.au/itm/GENUINE-...cAAOSwsPNcED7M
LS LT Focus Cabin Filter.pdf