Well, I got that mail too and I also use a 1€ server of ionos, but the mail only mentioned the price of plesk.
When I looked at the service page plesk wasn’t lizensed. So, are your sure you lizensed plesk? Because my usecase is fairly similar to yours…
Or did I got something wrong?
I use Trilium and I like it. The first thing I would like to mention: Trilium is stale and there is Trilium Next the official successor… More or less… If you choose to try, start with the one that is still in development.
But to be fair, I does not use it as I wanted to. My plan was to use it completly with markdown but I am to dumb or ignorant to do it right. So I simply use the wysiwig style integration to style my texts.
I will watch a video that shows me how to properly use markdown in there.
On the other hand, actually I think about switching to some AsciiDoc Notes/Wiki stuff. Simply because I like the way AsciiDoc works…
And the last to mention: I have no experience with Authelia.