How to test things locally?

I was trying to setup a Nextcloud server, but I screwed up every time, culminating to me being banned of issuing certificates from Let's Encrypt for a week.

Because I have no idea what am I doing, is there a way to play around on my machine before attempting anything stupid again?

I guess what I'll need is a docker image from Linode (could not find where they are hosted), then ssh into it and then do the stuff I want to do. After that - probably edit /etc/hosts on my machine to "pretend" of having a real domain. I totally suck at server admin stuff.