Docker is still supported, it’s now called Home Assistant Container. See HERE for an excellent post describing the current installation methods.
If you want the Supervisor, you have a few options. I can’t see what sort of machine you are using, perhaps I’ve missed it, so 2 options posted;
If you have a Raspberry Pi, you can use the official docs HERE and install Home Assistant OS, or you can run Home Assistant Supervised by following this guide.
If you are using a PC, Laptop, NUC, one option is to run Home Assistant OS as a virtual machine using Proxmox , or run Home Assistant Supervised using Debian 10.