Well technically that is what you're asking
cause if you were able to create a server than there would be literally thousands and THOUSANDS of sro servers.
If you want a good nice and stable private server you need years of experiences in coding and networking and you also need a team of at least 8 0 10 people.
So that's why you get these answers:P
It's just extremly difficult cause you need to reverse the whole server side which is a lot.
and you might notice those few private servers which are out and thinking but how did those started. well the exact story is too long to tell right here but short version. someone stole/hacked or leaked those files from csro(If i'm correct) and with those files are these private servers hosted. so that's why they all look the same cause they can't expand them with new legends cause it's not available in their files.
all they can do are some little changes faking some new skills ect.
The closed free to use emulator which is the best is from srevolution. (xcoding.net)
It's quite buggy but it has quite a lot features but it's not like it can support 2000 players online.