Problem installing Kiwix via Portainer on Raspberry Pi 4 on Umbrel

Dear Umbrel Community,
am relatively new here and have recently started experimenting with Umbrel. I am running it on my Raspberry Pi 4 with 8GB of RAM and an NVME SSD. I have Portainer installed and am attempting to run Kiwix, a service I already use on other devices, on Umbrel.
My primary challenge lies in deploying the Docker container for Kiwix-serve. I consistently encounter the same issue, whether I attempt to install it through the CLI or the Portainer UI.

I followed this tutorial:(& many others) Setup and Install Kiwi... | The Homelab Wiki

Here are the problems I am facing:
Portainer:

CLI with wildcard and without wildcard:

All seem to face the same issue - Unable to find image even though I was able to pull it via portainer. Under “Images” I can see the image has been pulled inside portainer.
The image definitely exists: Package kiwix-serve · GitHub

I have also tried logging into docker-hub via cli, also did not help.

What am I missing here?
I remember deploying Kiwix the exact same way on raspberry pi os but cannot seem to do it via umbrel/portainer.
I have also deployed the same on my Synology Nas via Portainer but it seems impossible on umbrel.

What am I missing here. Please excuse me if this is a total noob question, I am trying to learn here.
any hint into the right direction would be greatly appreciated.

I suspect it has to do something with the volumes/mapping maybe?

Thank you!
Andre