Issue: access denied to use device /dev/ttyUSB0:
manlix@lab:~$ ls -l /dev/ttyUSB0
crw--w---- 1 root dialout 188, 0 Aug 17 11:09 /dev/ttyUSB0
Solution: add user to group 'dialout' and re-run Arduino IDE:
manlix@lab:~$ sudo usermod -aG dialout ${USER}