Install that, let it finish, then reboot your new Windows machine. When it's done, you can skip through all the screens saying 'No thanks' to everything, and when you finally see the Windows desktop you should also see the Bootcamp executable starting up automatically. After around 15-30 minutes you'll see your Mac rebooting by itself as Windows is finalizing the installation process (it usually takes 2-3 reboots until you can see the new setup screens). Then go ahead and Windows 10 will install. You're now booting Windows from the USB, next make sure to follow the usual steps for installation (you can also skip the activation tab if you still don't have a serial) and just format the partition with the biggest space in it (not the EFI boot one). Boot with the Windows/Bootcamp created USB drive pressing Alt/Option until you see the EFI drive (if I correctly remember the name) and press enter. Time to shut down the system, remove the USB with macOS and insert the one with Bootcamp. You'll now open Disk Utility, make sure to select 'Show all devices' from the list view, and format the entire drive as MS-DOS (FAT) with GUID partition map as scheme (it's fine to me). It will take a little longer than a usual macOS boot because it's loading from the USB (or SD if you did that). Having created both the USB drives (one for Windows Bootcamp and the other with a whole macOS), you can now reboot your Mac with the macOS drive inserted. (this is optional but I highly recommend it for a cleaner approach and peace of mind). Now save all your files in a cloud service and/or onto an external HDD/USB drive, logout of apps/services from your Mac, sign out of iCloud, etc. It will take some minutes, then you'll have your 'health pack' ready for whatever you want to do next (also for restoring back your Mac without the need of internet recovery for example). To do that, rename your external drive in MyVolume and then use one of those 'createinstallmedia' commands provided by Apple in Terminal. Download the latest Mojave or Catalina or Big Sur from the Mac AppStore to then create another USB (or SD card too if available) drive with the whole macOS on it (8gb required for Mojave if I remember correctly, 16gb for the other two). Uncheck the option to trim the space on your drive and directly install Windows afterwards. Use Bootcamp Assistant to create a bootable drive with Windows 10 previously downloaded (you can find it on the official Microsoft website) and a 16gb USB drive. Make sure you're on macOS (whatever version, I would suggest trying Big Sur already as it will also install the new boot chime on your Mac, and that's cool ). I have installed the latest Windows 10 as my sole OS on my 2013 MacBook Air and this is how I did it:

Install windows 10 on macbook air 2020