If you look at the command you shared with us, “git clone -b noetic-devel https://github.com/ROBOTISGIT/turtlebot3_simulations.git”, ROBOTIS-GIT has been changed to ROBOTISGIT, and it seems that the link destination does not exist.
In addition, there have been minor changes to the documentation, and the branch has also been changed from noetic-devel to noetic.
Based on the above, it is possible that there was a mistake made during the environment setup, so we recommend deleting the ws you created and following the steps in the robotis e-manual to try again.