Have you tried using something other than pymakr? maybe screen or minicom. Also its worth checking if your user has permissions for the serial port. The procedure to do this varies by linux distro but on most you can add your user to the dialout group and when you reboot that user will have permissions to use serial ports
I got this to work on a different pc with windows 10, 32 bit installer of the the visual studio code (even though windows 10 install is a 64 bit install). 64 bit install of the visual studio code didnt work with the pymakr plugin for me.