Arduino Uno is not communicating with Maxuino. Help!

I am a newbie to most of this, so be gentle.

I’ve purchased an Arduino Uno, downloaded the most recent software, and followed this tutorial (although it is old, and the Maxuino patch has been updated and the interface has changed from the pictures provided. I have the most current version of Maxuino from their website, named b016.).

I’ve looked, and apparently the Uno does not require any USB drivers to be installed, so I don’t think that is the issue. I’ve downloaded the most recent firmata (2.3.6) and replaced the old Firmata folder in Arduino’s library, and the LED I hooked up to pin 13 blinked, so I know that it installed once I uploaded it. I closed out of Arduino, went to the maxuino.maxhelp, selected the same port (usbmodemfa131) as in Arduino IDE. When I click on the metro toggle to “test LED” after selecting pin 13, nothing happens. Am I missing something?
As a side note, when I open the maxuino.maxhelp patch my arduino’s LED blinks rapidly for a moment, acknowledging that Maxuino has been opened, so Im not sure why I cannot get it to control the LED. Any help would be appreciated.