There is no need to disable avast and make your system vulnerable to infections if you want to download something.
In fact it is a foolish thing to do.
It is like getting a good security system for your house but not having it active.

Ofcourse avast is asking if you are sure.
You are trying to disable a major part of the protection of your system.
Guess what can happen if you click on “disable the protection” by accident…