Installing a non-free deb package into Ubuntu 16.04

Hi, I have been using Corel Aftershot Pro 3 for Linux under OpenSuse and it is fantastic. Recently I bought a new laptop with 12Gb RAM so that I could run post production work away from my desktop, and so I have downloaded the deb package for it, but unlike my experience of RPM, the deb/Ubuntu experience is abysmal. I have tried double clicking on the package in my Downloads folder, but nothing happens. On a Ubuntu forum it was suggested that an upgrade would fix the acknowledged issue, but it hasn't. 17 years of RPM has not equipped me for this. So I would appreciate hearing where I have gone wrong and how I could get it right. Gratefully Andrew Greig