The Appimage format is a universal installer for Linux distributions. You can discover more about Appimage at http://appimage.org/. On modern distros, the applimage should be double-clickable. On older distributions of Linux you may need to explicitly make the file executable (eg chmod a+x dbkoda-latest.Appimage).
The current linux installers need a glibc version of at least 2.14. That will be fine on Centos 7 or Ubuntu 16.04 or later. On earlier versions of Linux, you can either update your glibc version or install dbKoda from source.
On Centos 7, we observed the following issue:
error while loading shared libraries: libXss.so.1: cannot open shared object file: No such file or directory As a workaround, sudo yum install libXScrnSaver