You're welcome.
Only thing I can (and did) is providing information with the knowledge I have.
Nothing more, nothing less (as they say)
I don't have any indication at all that you don't have a legitimate version.
If you have downloaded through a browser...
Almost(?) all browsers have a place where you can see the downloads.
I would check there (if possible) to see where you got avast from.
If it is CNet or avast, you don't have to worry if you have a legitimate version or not.
You will have one.
Just some suggestions...
Go through the settings and look at them.
Learn what they are about, what they do etc.
It may become handy to know these things.
I find this a good practice for all software.
Sure, it will cost you (some?) time to do so, but it can prevent problems