HA OS Bare Metal - no add-ons?!

Hi, just changed over from Proxmox to a bare metal installation. I'm trying to restore HA from the cloud.

https://preview.redd.it/r1z2dvu8anyf1.png?width=1066&format=png&auto=webp&s=65d1492bfd5bf49f61cc4d891d92bccff79465b5

It tells me this installation method does not support add-ons?!

I thought that was a container-in-a-container issue? But it has the whole hard disk for itself, it's not a container (it's in Proxmox but there it works?)

Um, help? And please don't hold back on telling me what stupid little thing I'm missing...