brent Yes, Brent, you are right! I did the chmod +x on it, and now it is executable. Thank you!!
Then all I had to do was double-click on its icon, and follow the directions, no need to even use terminal. It gives the option to install GPS (Gnat Programming Studio) separately, which is a good idea, because then you can install GPS in a separate directory. Then you just have to add the paths to the $PATH environment, and it all works fine, I still think it would be nice, if Solus had Ada in the repository, though. Ada is not anywhere near as popular as it was 30 years ago, but it is a solid language, with many features like Java, and has constantly been updated and improved.