Its rather easy..
Cause you antivirs are all hyperactive and shit. They will flag it for no reason.
Note: download the zip without unzipping it won't to shit anyways, and even with unzipping is veeeeeery unlikely anything can happen. So you could tell your antivir to stop blocking (or turning it off for a moment), download it, unpack it and then scan the FOLDER with the same antivir and see what it says. Lol gurantee it will say its fine. (For shits and giggle scan the zip thats downloaded too lol).
There is no virus, in the zip/file etc.