Envirgrow not uploading

Hi - I am new to Pi’s and have already hit a wall. I have an envirogrow running the default scripts but it will only upload to adafruit if I manually run main.py. I have upgraded the firmware but no luck. It is extremely difficult to connect to Thonny usually with the error: Unable to connect to /dev/cu.usbmodem142101: [Errno 2] could not open port /dev/cu.usbmodem142101: [Errno 2] No such file or directory: ‘/dev/cu.usbmodem142101’.
The odd time it does connect it will often hang up and time out before a script can be run.
Any help would be appreciated as so far envirogrow has only been a lesson in frustration.