First, Wemos has a serial/USB chip based on CH304G. This is the same chip found in cheap Arduino-clones and you must install a proper driver for Mac or PC. Follow the instructions on this site to install the driver. Connect Wemos to your computer and confirm that your computer could detect Wemos. On Mac, run the following command and you will see a device called /dev/tty.wchusbserial640.
is it on the WEMOS Board or should i add them on a breakout-board!?