The ancestry.com dna file will be labelled this way:

dna-data-year-month-day

For example, a file that you downloaded today would be labelled as:

dna-data-2014-11-13

Don't rename or unzip the file (per gedmatch instructions). I keep track of whose data it is by moving it into a labelled file folder (example - folder labelled "charkensil raw data" but keep the original file name the same.