This post will show how to start stop Virtualbox with systemd. The documentation for both auto-starting virtualbox and that for systemd I found to be appalling. The virtual box documentation has an example but that is wrong. The example code is bash and it is sourced by another file. There is a variable assignment at the top but it has spaces around the equals so it fails with a schoolboy syntax error. For systemd what there is, and there is a lot of it, does not make sense. The man pages have lots of English words that go together to mean nothing but the usual marketing bullshit we are constantly get bombarded with.
This is a side by side translation of Perl and PHP. There may well be better ways to do it, this is one way.
There other pages similar to this, all the pages I could find were somewhat out of date.