The solution to that is also very simple: don't use example.com as an option to certbot if you don't want to use that domain name.
It looks like you blindly copy/pasted an example from the internet without actually knowing what all the different options do. This is very bad! You should, before you hit enter, always verify you know what all the options actually do. In this case you should look up the function of the -d option in the certbot documentation.
Why would you try to use non-existing files in the first place?
I would urge you VERY STRONGLY to try to use a little bit more autodidacticism when it comes to following certain guides. This because it really seems you're blindly following a certain guide without actually understanding the reasons behind certain steps, what the effect of certain steps would be et cetera.