When working with Arduino boards for the first time, you're bound to make some mistakes, but these are some of the most common pitfalls you can avoid.

I took his project and used the Teensy2 instead of an arduino as well as seperate red, blue, and green LEDs since I had some lying around.

In fact, that’s how the Arduino IDE flashes the board. This should have been obvious since the board is really just a breakout for the SAM D21 chip which is already supported.