Download px4 + gazebo then in px4 folder
make px4_sitl_default gazeboDownload QGroundControl and:
chmod +x QGroundControl.AppImageDownload ROS Melodic desktop only version
Download mavsdk newest version
Make catkin_ws folder, add this repo to src and catkin_ws folder:
catkin_makeif everything is okay
roscore
rosrun mavsdk_interface node udp://:14540
source devel/setup.bash