Hi @JRTG ,
Ok, I just realized you were on ROSDS environment. I thought you were on course environment.
Anyways, try these in order and let us know!
cd ~
source /opt/ros/noetic/setup.bash
source ~/simulation_ws/devel/setup.bash
rosrun turtlebot3_teleop turtlebot3_teleop_key
These lines are already mentioned in the ROSDS rosject notebook.
Regards,
Girish