Install tmux latest version on Ubuntu 16.04/18.04

sudo apt install automake build-essential pkg-config libevent-dev libncurses5-dev -y

VERSION=3.0a
wget https://github.com/tmux/tmux/releases/download/${VERSION}/tmux-${VERSION}.tar.gz
tar xf tmux-${VERSION}.tar.gz
rm -f tmux-${VERSION}.tar.gz

cd tmux-${VERSION}
./configure
make
sudo make install
cd ..
sudo rm -rf /usr/local/src/tmux-*
sudo mv tmux-${VERSION} /usr/local/src

sudo killall -9 tmux
rm -f ~/.tmux.conf
git clone https://github.com/tmux-plugins/tpm ~/.tmux/plugins/tpm
wget https://gist.githubusercontent.com/Dibbyo456/0352ad3bd9ecc68a659c73d5ccc528fa/raw/.tmux.conf
tmux source-file ~/.tmux.conf

Enter into a tmux session.

Shift + I (captial i) –> Install plugin.

Shift + U  –> Update plugins.