I am new to the PX4development area: roslaunch ofboardpy startofb.launch (I have named my real files as ofboard and start_ofb aswell (not a spelling issue))

following the tutorials I am getting this error:

RLException: while processing ~/PX4-Autopilot/launch/posixsitl.launch: Invalid roslaunch XML syntax: [Errno 2] No such file or directory: '~/PX4-Autopilot/launch/posixsitl.launch' The traceback for the exception was written to the log file

I have ensured that the address is correct and can cd into exactly the ~/PX4-Autopilot/launch folder

I am running noetic on 20.04

not sure what else can be the issue