I had a small hiccup today while trying to install a bot. I was advised to install RVM looked for a simple install instruction was able to find one. So I created one.
The errors you might deal with is mostly permissions.
Ruby Version Manager (RVM). A command-line tool which allows you to easily install, manage, and work with multiple ruby environments if your apps or projects need different versions of ruby.
I forked a github and modified it a bit for current install instructions.
gpg2 --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
curl -L https://get.rvm.io | bash -s stable
source /etc/profile.d/rvm.sh
rvm install 2.2.2
rvm use 2.2.2 --default
ruby -v
gem install bundler