Out of curiosity I tried now with a hAP ax3 and it works perfectly!
I checked on hAP ac3 and everything works. Perhaps something with the RB5009, but I don’t have it to check
It is interesting, is anybody has positive experience installing HA on RB5009? 
In a quick test on RB5009 (arm64), I get a layer error (specifically, “error getting layer: resolving error” when downloading a layer). On RB1100Ahx4 (arm/v7), it imports and goes to start.
There is a Traefik container that works fine on same RB5009, so /container is enabled/working otherwise. You might want to try an older tag of HA instead of latest, dunno.
It should work since Mikrotik specifically documents how to set it up: https://help.mikrotik.com/docs/display/ROS/Container+-+HomeAssistant
Finally make it work… 
a) Reset docker settings
b) docker pull homeassistant/home-assistant:latest@sha256:17d159928122e6f374bd39b0e75904522bc7d7c2a64e88b248948734e4c4d444 on my host machine
c) docker save -o ha_arm64.tar
d) Upload it to router
e) /container/add file=“usb1/img/ha.tar” interface=“veth1” envlist=“envha” cmd=“python3 -m homeassistant --config /config” hostname=“homeassistant” workdir=“/config” root-dir=“usb1/containers/homeassistant” mounts=“homeassistant” logging=yes
Now it works and I can access it.
However I have 2 questions to solve
a) I need ffmpeg inside of the docker. It eats like it is not there.
b) The container is in 10.10.0.1 and all my devices are in 192.168.88.1. And it seams like 10.10.0.1 is not visible from within 192.168.88.1. So I can’t add the home assistant as a hub to Apple Home so far.
UPDATE:
ffmpeg is there but working with some errors. But it is not related to Mikrotik for sure 
To all:
It is not possible to pull the latest image or even stable image of homeassistant for arm64 on Mikrotik RB5009, because the size of image is more then 1.5GB, but the storage on RB5009 is only 1GB,
you must change your settings in container to use usb disk for pulling-downloading images:
container/config/set tmpdir=usb1/pull
Best regards!
Using Docker for windows I got the first command to go thru but not the second listed below
docker pull homeassistant/home-assistant:latest@sha256:17d159928122e6f374bd39b0e75904522bc7d7c2a64e88b24
The error I get is:
PS C:\Users\allan> docker save -o ha_arm64.tar
“docker save” requires at least 1 argument.
See ‘docker save --help’.
Usage: docker save [OPTIONS] IMAGE [IMAGE…]
Save one or more images to a tar archive (streamed to STDOUT by default)
Even if “ha_arm64.tar” wasn’t bound as the option to the -o flag, making it unavailable to be interpreted as the “IMAGE” argument, it it isn’t an “IMAGE” in the context of that command at all. The -o flag names an OCI image archive, not the same thing. The “save” command wants the actual input image name:
docker save -o ha_arm64.tar homeassistant/home-assistant:latest
Beware the documented limitations of the HASS container. I faced this decision myself just yesterday, and while I found lack of one-click upgrades of little concern — the container engine handles that for you — lack of add-on support and broken backups doesn’t work for me at all. I went with the HAOS VM image instead, now running on my NAS.
Has anyone found a solution to this problem. The image is showing in usb1/pull as a tar.gzip file, was around 300mb but now showing as 171B.
I am using Mikrotik L009 which supports container and advertises that it supports home assistant.
I am following the Mikrotik instructions to the letter.
Any help would be appreciated.
See my previous message:
http://forum.mikrotik.com/t/home-assistant-container-does-not-starts/176885/1
I have the same problem with hAP ac2 and I have never been able to understand the cause.
having same problem with caddy image on my hap ax3. worked for almost a year with no problem, but now - it manages to pull container every 5th time, otherwise - error.