Because i do not have MINT installed on any machine, tested with VirtualBox.
Mint 19 Cinnamon
Yes, it does not work if only make symlink to libssl version 1.0.2, on Cinnamon you have to make symlink also for libcrypto 1.0.2.
With Synaptic Package Manager installed rpm
then:
rpm --install RenderMan-InstallerNCR-21.7.0_1837774-linuxRHEL6_gcc44icc150.x86_64.rpm
then made two symlinks:
ln -s /usr/lib/x86_64-linux-gnu/libssl.so.1.0.0 /opt/pixar/RenderMan-Installer-ncr-21.7/lib/3rdparty/Qt-5.6.1/lib/libssl.so
ln -s /usr/lib/x86_64-linux-gnu/libcrypto.so.1.0.0 /opt/pixar/RenderMan-Installer-ncr-21.7/lib/3rdparty/Qt-5.6.1/lib/libcrypto.so
run installer
click OK
Chose what you need (use Show All if needed)
Also tested with official Blender-2.79b, because for me RenderManForBlender does not work with git builds, seems that is not compatible with Python-3.6, but i can be wrong.
So, extracted blender-2.79b-linux-glibc219-x86_64.tar.bz2
Downloaded RenderManForBlender from https://github.com/prman-pixar/RenderManForBlender
but not release, you need latest master
Clone or Download → Download ZIP
Installed Addon from ZIP
Enabled, Saved preferences
Chose RenderMan Render
and: F12
Hope it helps. 