Download .gz files from http server

Hi there

I need to download yearly data (gzip compressed files) from CDDIS | | archive | gnss | products | troposphere | zpd | (nasa.gov). I have tried webread, websave,urlread, rulwrite, but all of these commands are not working. Usually, I use gunzip to extract/download data from gz files and always works well. However, this time, its not working either. The attachment presents what I have after using gunzip. Any suggestions will be appreciated.