Your keyboard is flashed and ready to go! You can use it straight away.
Just make sure it is turned on (the switch below the USB port, the screens will come on when it is powered. If they do not come on, make sure the battery is charged). Once it is powered on you can add it as a Bluetooth device to your PC.
To quickly and easily make changes to the keymaps, go to https://zmk.studio/ (you can only edit it when plugged in via USB through the web portal) or go to https://zmk.studio/download to download the desktop app to be able to edit your layout wirelessly.
If there is delay when typing, it's likely due to a weak connection to your PCs antenna. Try bringing it closer to troubleshoot and find the right distance.
Files
Your keyboard is already flashed and ready to go, but if you need to reset your keyboard or have any issues, you can use the below files. To re-flash you keyboard:
Double tap the GND & RST pin with something conductive with the USB inserted. (you can use some solder or tweezers)
A file explorer window will pop up, download the respective file from the tabs below and copy that files into the directory. The windows should automatically close.
Unplug the USB cable from the flashed side and plug into the other half.