Using duplicator original to clone, clone to original

Hi I just wanted to ask a question before I start using duplicator. I want to work on a layout under a subdomain and then transfer it to my main website. I thought using duplicator would be the easiest way as i am not sure how to do it manually

But before doing this I just wanted to test duplicator by creating an exact copy of my website to the subdomain. Will anything happen to my original website if I do this?

. When I create the folder for my subdomain does it have to be empty before I use duplicator, or do I have to install wordpress on it first?

I tried it earlier with the subdomain already installed with WordPress and got this error:

INSTALL ERROR!
A configuration file already exists in this location. You have two options:

Empty this root directory and recopy the package and installer.
Copy package from “wp-snapshots” directory back up to your root (same location as installer.php) and delete the wp-config.php file.

was wondering whether the subdomain directory should be completely empty, as earlier i was just going to overwrite the existing database but got that eror