The Macbook Air has Thunderbolt (USB-C) ports on it. Get a Thunderbolt to HDMI adapter, then just plug it into your projector. As a owner of a computer without standard HDMI connectivity, you should have a proper Thunderbolt to HDMI adapter you carry with you everywhere so you can make a connection when you need to.
I've used one for a couple of years without issues. Similar to this one...
https://www.amazon.com/Anker-Aluminum-Pixelbook-Compatible-Thunderbolt/dp/B07THJGZ9Z
Then just use any standard HDMI cable to connect to the projector. USB is not a video standard. HDMI is. Thunderbolt is as well. USB-C, is not actually a video connection standard, though USB-C has some versions which do support video, and aren't specifically 'Thunderbolt'. But, at the end of the day, Apple likes Thunderbolt over USB-C, which means you have a HDMI compatible connection on your laptop right now.
Important to understand, at a basic level, that this is how it works. USB-C = data. Thunderbolt = a lot more than data, including video connectivity.
With that Thunderbolt to HDMI adapter, you can then connect your laptop to any HDMI equipped device in the world. Though, Apple likes to still be obnoxious about compatibility.
For those of you looking for a usb c to HDMI adapter that works with RP2
This one from Amazon works.
It is also available at Target online/in store, for those who hate online shopping. They WILL pricematch the Amazon price!
Here is what I would recommend.
mics
https://www.amazon.com/innopow-80-Channel-Microphone-Continuous-WM-333/dp/B0749L15PF
mixer
https://www.amazon.com/BEHRINGER-XENYX-1202FX-3-pin-Black/dp/B000J5Y214
speaker(s)
https://www.amazon.com/Mackie-Thump12A-1300W-Powered-Loudspeaker/dp/B073V7MKQZ
cables
https://www.amazon.com/Cable-Matters-6-35mm-Inch-Male/dp/B00KO8VZ1Q
https://smile.amazon.com/Hosa-CMP-159-Stereo-Breakout-Cable/dp/B005HGM1D6
https://smile.amazon.com/Cable-Matters-2-Pack-Microphone-Feet/dp/B00KO8VY4O
https://smile.amazon.com/Anker-Aluminum-Pixelbook-Compatible-Thunderbolt/dp/B07THJGZ9Z
mic covers
https://smile.amazon.com/Handheld-Microphone-Windscreen-Anti-Roll-Device/dp/B07C15R65M
Update 4/21/22: Got my 25' long HDMI cable and USB-C to HDMI adapter Amazon: Anker adapter . (I decided to go too long w/ the cable instead of being too short) I plugged in one end of the HDMI cable into my HDMI 3 port where the Chromecast used to be. Plugged the other end of the HDMI cable into the Anker adapter, and plugged that into my computer (Windows). It played exactly what was on the TV, cursor and all. The screen on the computer had to be on, or there was no picture. Next I used the same adapter in my iPad Pro. When I stream from that from MLB.TV app At first I didn't think it would work, but it's working. The iPad screen is black (which I want, actually) but showing me the game on TV. I didn't have to use the streaming icon on the app, and there isn't one when I do it from the computer. I think a Roku stick or Chromecast would work also, I think the Chromecast I have is old. Thanks everybody for helping me solve my problem, and now I can watch the games on TV!!
Get a type C to HDMI. Such as this one from Anker, which makes decent quality stuff. https://www.amazon.com/dp/B07THJGZ9Z/ref=cm_sw_r_cp_api_i_9PR7NP9C3Q54Y4HB5PAR