The recommended version of Linux for all versions of Paratext is Wasta-Linux 18.04 or Ubuntu 18.04 (Bionic).
Wasta-Linux is a customized version of Ubuntu, specificially designed for language work. It makes installing SIL language software much easier and provides a free alternative to operating systems like Windows or Mac OS X. Wasta-Linux uses the same version numbers as Ubuntu.
Paratext can be downloaded from the SIL Linux repository. You can either use the software or package manager to find the Paratext versions you wish to download, or download Paratext with a terminal command like the following (for Paratext 9.0):
sudo apt install paratext-9.0