From the Readme

(Slightly edited for clarity by Zooberry but otherwise unchanged.)

Installation instructions:

(For Windows XP/2000/+)

After unzip the zip-file you must save the folder “ZTABC” from the Download-folder in the Microsoft-folder from Zoo Tycoon 2. C:\Documents and Settings\All Users\Application Data\Microsoft Games\Zoo Tycoon 2\downloads\

(for Windows Vista)

After unzip the zip-file you must save the folder “ZTABC” from the Download-folder in the Microsoft-folder from Zoo Tycoon 2. C:\ProgramData\Microsoft Games\Zoo Tycoon 2\downloads\

If you want to download the “ZTABC” order right away, simply copy the “XXX.dl” file and the “XXX” order from the download. If the folder “ZTABC” already exists, just copy the “XXX.dl”- file and the folder “XXX” to there.

Zoo Tycoon ABC

And lots of fun to play. / Have fun.