Depending on how well you know your way around, my recommendation is to not use the Ansible setup but instead treat it as documentation while doing things your way. It has quite a bit of strange stuff going on (postfix? two nginx installs with only one being in a container?) and seems to be missing important things such as SSH hardening. It also assumes it'll be the only thing running in your server just in general (horrible yet common practice, unfortunately) so if you have anything set up it may or may not clobber over it to do things it's own way, and end up breaking something.

Also, can you log in to wefwef through your instance, or how do you access everything, specifically on mobile?

I haven't tried wefwef in particular but all native apps I tried work just fine. An issue I can see cropping up from wefwef is that Lemmy's CORS policies are way too restrictive by default. No idea if they do any kind of proxying to get around that but that would be the main issue I'd imagine.

The installation itself is pretty simple, every piece of lemmy lives in a docker container, so they should work right out of the box. The admin configuration has a slightly unintuitive UI but alas very few things to do, so really small leaning curve.

Guide: https://github.com/LemmyNet/lemmy-ansible

There are many guides on getting started with Linux servers as a whole. I recommend installing Debian Bookworm on a virtual machine or a spare laptop at first and going through the writeups all major cloud providers have, just to get a feel for using the terminal & initial setup (SSH hardening and reverse proxy configuration and so on)

After getting an initial feel for Linux admining, start reading up on Docker, Docker Compose, and containers in general. Avoid Podman until you're experienced with Docker as it's just different enough to trip you up. You can also check out LXC/LXD although it's way less popular.

Oh, and speaking of Docker: UFW AND DOCKER WILL NOT WORK TOGETHER! DOCKER BYPASSES UFW (just making sure you don't learn this until it's too late)

Be careful of guides that are old (even a year makes a difference) or for different "distros" than the one you have. An exception for the second case is the Arch Linux wiki, which is one of the best resources just in general, aside from a few Arch specific bits like the exact package names to install. You should also use Arch's "man pages" reference, as they're built from the latest versions of packages compared to other man page renderers that are frequently outdated (like die.net)

Lemmy itself is harder to get right because the instructions so far are intended for people who kinda know what they're doing, but once you have the base Linux admin knowledge, it won't be that hard to pick up the parts necessary to get working with something like Lemmy.