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Usually, rvm.io documentation is pretty good about guiding you through the ruby install process. It does depend on your specific operating system. But on ubuntu, it boils down to:

gpg --keyserver hkp://pool.sks-keyservers.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
curl -sSL https://get.rvm.io | bash -s stable 
source /home/tender/.rvm/scripts/rvm
rvm install ruby-2.6.0
gem install radiator

Thanks a million, I will definitely check that out