Re: No download button
If you log into via admin and go to configuration - attribute settings, how are you r settings configured for downloads? I believe by default the installation of Zen Cart keeps these off as most people do not run sites that have downloadable products. I would start there first.
Best of luck 
0be1
"Give me one hundred preachers who fear nothing but sin and desire nothing but God, and I care not whether they be clergymen or laymen, they alone will shake the gates of Hell and set up the kingdom of Heaven upon Earth." - John Wesley