I did not see this file on the sd card after installing RPi OS Lite.
Per https://www.raspberrypi.org/documentation/configuration/wireless/headless.md it should be created and added. I used Notepad++ to do this.
I also found using Advanced IP Scanner it did not show “Raspberry Pi Foundation” as Manufacturer, whereas on my other RPi’s it did.
Did you have any issues connecting to your network? I made the wpa_supplicant.conf file and triple checked my credentials but still no luck.
Thanks for the response! Can you explain? I tried connecting the RPi OS lite to my network using the wpa_sup file but it wont seem to connect no matter what I do.
Yes, I had the same issue. So you will first have to connect a keyboard and monitor to the RPi. Then log in and run
sudo raspi-config
Select “System Options”, then “Wireless LAN” to set the network up.
Hello Jack, Christian and anyone who needs help in this step for building your drone! You won’t need a keyboard or monitor for the RPi 
a. Insert the SD card in the usb reader and insert the usb reader to your computer.
b. Download Raspberry Pi OS Lite (2021-01-11-raspios-buster-armhf-lite.zip).
c. Extract the Raspberry Pi OS Lite zip file in a folder.
d. Download and install Etcher (Etcher-Setup-1.5.116.exe).
e. Open Etcher, select the image where you extracted the Raspberry Pi OS Lite zip file.
f. Flash the OS into SD card.
g. Remove and insert the SD card back again.
Note: Raspberry Pi OS Lite is the Raspberry Pi Operating System. Etcher is used to flash the operating system into the SD card.
a. Download and install Advanced IP Scanner (Advanced_IP_Scanner_2.5.3850.exe).
b. Download and install Putty (putty-64bit-0.74-installer.exe).
c. Download and install Notepad++ (npp.7.9.3.Installer.exe).
d. Create a text file named wpa_supplicant.conf. (Remove .txt extension if any.)
e. Use Notepad++ to open wpa_supplicant.conf which is in the SD card.
f. Copy and paste the following:
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=<Insert 2 letter ISO 3166-1 country code here>
network={
ssid=“Name of your wireless LAN”;
psk=“Password for your wireless LAN”;
}
g. country = US if you live in the US.
h. Edit with your wifi name and password.
i. Save the file.
j. Create a new txt file named ssh and remove the .txt extension.
Note: Advanced IP scanner is used to help us find the random IP address assigned to RPi when the RPi connects to the internet. Putty is used to secure shell (SSH) or remotely access the raspberry pi by using the IP address. Notepad++ is used to access certain files in the SD card.
a. Insert the SD card into the metal slot of RPi.
b. Power the RPi. Wait for 90 seconds up to 2 minutes.
c. Launch Putty and type raspberrypi for host name. Port should be 22.
d. Click open. Login as pi. Password is raspberry.
You should be able to remotely access the raspberry pi now. RPi is connected to the internet.
Note: To power the RPi you can use a micro usb C cord or connect it to the power distribution of the drone. The RPi can turn on a yellow light indicating that it is setting up something and it is not ready yet to be logged or used. A solid blinking red light means that the RPi is ready to be SSHed.
I hope this helps!
I would like to point out that you will still need a keyboard and monitor as the RPi dont come with SSH enabled by default anymore (to prevent them from becoming part of a botnet) and you will need to go in a make a SSH file in your boot drive and also you will need to go in using keyboard/monitor to enable SSH in raspi-config. There probably is another way to do it without using keyboard/monitor but idk how to do it.
I explained in my message above on how to ssh into RPi without monitor/keyboard. You experienced any issue following the steps?
Yes when I was doing this step you have to make a ssh file and enable ssh in raspi-config now.
Hi Laptus. You don’t need a separate monitor/Keyboard as Elis explained. Take out your SD card and insert it to your personal PC or mac and just add the SSH file like just like adding any other file to a flash memory and then put it back to your Rpi
I encountered this same problem and also saw this today. You can set what you need while imaging if using the “Raspberry Pi Imager” software to image. The raspberry pi imager software now comes with hidden options to enable wifi and ssd: https://www.tomshardware.com/news/raspberry-pi-imager-now-comes-with-advanced-options