Local use of NC and Collabora - tutorial?

Hi, I have been searching for some kind of tutorial to start using Collabora CODE but have not found any.

My setup, a fresh Ubuntu server with NC on a NUC. A windows laptop with chrome to access NCs www-interface.

The status right now:
In Settings => Administration => Collabora Online: “Collabora Online server is reachable”
It is set to “Use the built-in CODE”

But when trying to open a document I receive the following message: Failed to load Collabora Online - please try again later.

Any help is most appreciated.

// F1663R

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