You need to have previously installed ROS2. Please follow this guide if you don't have it.
source /opt/ros/jazzy/setup.bash
Create workspace and clone the repository
mkdir ~/tiago_ws/src
cd ~/tiago_ws/src
git clone https://github.com/Tiago-Harmonic/tiago_harmonic.git -b jazzy
vcs import . < tiago_harmonic/dependencies.repos
Install dependencies and build workspace
cd ~/tiago_ws
sudo rosdep init
rosdep update
rosdep install --from-paths src --ignore-src -r -y
colcon build --symlink-install
Setup the workspace
source ~/tiago_ws/install/setup.bash
ros2 launch tiago_gazebo tiago_gazebo.launch.py is_public_sim:=True world_name:=house # or empty