I'm just trying to get this WiFi blaster working but the program won't compile. I thought avr libraries were automatically set up? Sup...……...
Which board do you have selected from the Arduino IDE's Tools > Board menu?
Please post a link (using the chain links icon on the forum toolbar to make it clickable) to where you downloaded the IR library from. Or if you installed it using Library Manger (Sketch > Include Library > Manage Libraries in the Arduino IDE or Libraries > Library Manager in the Arduino Web Editor) then say so and state the full name of the library.
avr/interrupt.h damned well better be available - but only on AVR-based boards. Boards based on other architectures may have their own libraries that serve similar purposes.
Many libraries and code samples for Arduino that you might find around the web, though, are for AVR boards only, often just classic AVR, or sometimes just a couple of specific microcontrollers (most often the 328p, 32u4, 2560, the ones used on the official AVR boards, and with which people are most familiar). They may or may not bother to mention that in their documentation, but if it's trying to include an avr library for a non-avr board (which would be the only time you'd see that kind of error barring very strange pattern of missing built-in libraries, that would point to the library/code only supporting AVR