I can't spawn but others can

I think this has to do with the amount of files I don’t have from a server.

Every time I signed into a server, it shows how much files I need, if I have less then about 100, I can build.

If I don’t, it doesn’t let me spawn anything. That happens with every server because I need 200+ files, even with build rights I still can’t.

And I don’t want to download files from a server.

There’s your problem.
Just don’t join servers with like 133/7 players.
(Right click -> View Info -> Check if the number of players visible in the box is equal to the number of players it says with the numbers.)

I didn’t it was a server of 18/20 people, I didn’t get infected either.

There was actually 18 people, and I don’t want to start a server by myself and be alone for an hour.

I’m asking : Why the fuck can’t I spawn but everybody else can.

When you said you didn’t want to download stuff from other servers, I assumed you had disabled Downloading from other servers in Options. That could be the cause. If you have, enable it again.