Can't connect to Digispark Pro

[JeffHoover]

TL-DR: I can't program my Digispark Pro.

I bought this:
https://www.amazon.com/gp/product/B011AVTWHY/
Digispark Pro. I downloaded the Arduino software 1.6.11 (for Mac)

I added this board manager:
http://digistump.com/package_digistump_index.json
and under Board selected Digispark Pro (Default 16 Mhz).

When I plug a USB cable from it to my Mac, one red LED (power?) comes on solid and the other blinks a pattern - maybe 3 double-blinks (it goes fast), followed by a pause. Holding the reset button turns off the blinking light and, when released, the blinking resumes.

The IDE can't upload anything to the device, no matter which of the available ports I choose:
/dev/cu.Bluetooth-Incoming-Port
/dev/cu.Bluetooth-Modem

Does anyone have a suggestion?

[tr1p1ea]

I have to constantly reboot and change USB ports with my Digispark Pro.

It's not exactly a long-term solution however.