If you are okay with spending money, why not pay someone else do host the server and do the installation for you? https://namelesshosting.com by Partydragen and https://namedhosting.com by me provide this experience.
Or, if you still want to host it yourself, I'd recommend using our docker images for easy setup.
If this is not about webserver setup, please provide more information about your issues as cpk said as well
You can edit these in /custom/templates/*/email
It looks like you want username verification, why not use the spigot plugin to do this? https://www.spigotmc.org/resources/nameless-plugin-for-v2.59032/
By editing the HTML and adding `width` or `max-width` you can probably fix this, but ideally the website should have `max-width` on images by default.