Install Linux Apps: Lemmy, Pict-rs and mail

I have a shared VPS on Linode.com running Debian. I've installed Lemmy (https://join-lemmy.org/docs/en/administration/administration.html) using Yunahost. The app was running an accessible via links.fintech.eco but after me trying to get pict-rs installed manually, Lemmy / webserver has crashed. I'd like to get this fully installed so that it lemmy runs wiht pictures (pict-rs) and will send notifications emails.