How to create users in polylith docker deployment?

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polylith docker-compose file
polylith dendrite config

In which container should the command create-account be executed?
Currently there is no _admin endpoint mentioned in the docs, therefore blindly running the command in any container creates the following output:

/etc/dendrite # create-account --config=dendrite.yaml --username test
Enter Password: 
Confirm Password: 
FATA[0003] Failed to create the account: unable to get nonce: Get "https://localhost:8448/_synapse/admin/v1/register": dial tcp 127.0.0.1:8448: connect: connection refused