"Hi I want to play lan with my friends at school is there a cracked version I can use?"
Do you realize how fucking stupid you sound?
1 - You should just buy them. Why would you try and use a cracked version wtf? 2 - You are at school. You are at risk just by being at school. 3 - You don't even put like a specific fucking question. You don't put like what type of computers you're on or anything. Total fucking scrub.
If you were actually GOOD with computers and your friends were, you would know exactly what place you could pull this off and exactly how to do it. If you have to ask, you're a little bitch who shouldn't be doing it in the first place. Honestly what kind of advice were you expecting holy shit. As if it's just a matter of linking one universal file that you can just run and it works automatically. Jesus christ.
I'm like 8 years out of high school and I can't imagine pulling this off. You'd have to really know what the fuck you were doing. You'd probably have to have a teacher in on it. I know in my situation, there were very few computer labs that had Windows computers even and they were heavily protected. It would have to be like a fake "student teacher" session for a programming intro class. We'd have to like make a fake powerpoint and sell to a teacher to schedule a period of time to that computer lab and it'd have to be off hours to bypass a teacher presence. Then even if we just had access and didn't have to worry about teachers or computer access. Now you have to figure out how to bypass all the school firewalls and security bullshit. Almost all the accounts were marked limited access. So we'd have to like force safemode to bypass network boot and boot from like a portable USB. Even if you could just boot into it, now you have to figure out how to get Steam on or whatever bullshit "cracked version" on which is going to take up a significant amount of space and you'd have to hope to god it isn't a network synced profile. You'd have to delete the game otherwise.
The only way I see this working is if you and your friends find yourself in a special situation where you have access to computers off network grid where you can download directly to them and not a remote synced account, you don't have security issues, and you don't have a teacher supervising. But again, if you were smart, you'd know this is fucking retarded MOST LIKELY unless you go to some shit school that doesn't give a fuck about anything.
Bottom line is it is HARD to pull off. And the fact that you think you can just easily ask Reddit (of all places for fucks sake) and get a simple universal download link that works for any situation. Not to mention you have to know how LAN connections work and you need to get around the firewalls and that the ports will work. You'd need to know how to even setup a LAN game and use console to setup the rules and connect via local ip. You'd need to know how to use cmd prompt and just advanced computer shit. You can't just ask Reddit like what the fuck how did you get this far in life and you think this is a viable thing to do.
Just buy the fucking game and play online. OR just setup a real fucking LAN at someones house. OR look up an internet cafe and play CS there! Without breaking rules or risking anything. Like what the fuck.