cs go server can't change net_maxfilesize

Hello there,

I'm trying to host a server for me and my friends but unfortunatley I can't get the map download to work.

When I enter the server I'm getting kicked for "missing map".
I already located the problem: the server is set on
net_maxfilesize 16
The map is 30MB

When I try to change the maxfilesize it says that "net_maxfilesize" is an unknown command.
Here's a picture:


So can you tell me what's the command to change it or in which config or text file this setting is located?

Thanks