PC:
GPU: GTX 1050Ti 4GB
CPU: Intel core i3 7th gen 3,9 GHz
RAM: 8GB
by the way iam am talking about the ETQW from amazon

lol Obviously you can run a 11 years old game.
The last time, I played in Windows 8.1 64 bits, I dont think you will have any problem.
https://pcgamingwiki.com/wiki/Enemy_Territory:_Quake_Wars
There you will find a lot of info and fixes for possible problems, dont forget to update your game when you install it.
If the game you are going to buy is a second hand game, ask the seller if it includes manual, you cannot play online without the key that the manual includes.