[Edit: It is suspected that the failure is caused by the fact that the .run file is built for ubuntu 16 but the actual os is ubuntu 18. However the version built for ubuntu 18.04 cannot be found anywhere. So if you can post the link towards the version for ubuntu 18.04 it will be considered great help.]
Downloaded Radeon ProRender for Linux (labeled v2.0 for Blender 2.8) from radeon official website.
Though AMD claims Ubuntu 18.04 is supported, the installation file still warns that it "is built for Ubuntu 16.04 and continuing installation may encounter problems".
The installation was carried out despite the warning and the installation procedure was problem-free. However when Blender was launched afterwards, EEVEE and Cycles are still the only two renderers to be found.
By looking into the Plugin settings in Preferences menu, the Radeon ProRender can be found unchecked. The attempt to check it failed, with the following information:
NameError: name 'rpsdk_bin_path' is not defined
Please see the attached picture for more information.
How to solve this problem? Please help.