How do you setup a bundler for mining / forging child chain coins on the Ardor platform?
From the wallet cogwheel menu select the bundlers page and start a bundler.
You will need to specify your passphrase in order to run a bundler so you'll have to run it on your own node. You also need the node admin password in order to list the bundlers.
Here is some additional discussion https://nxtforum.org/general-discussion/ardor-child-chain-bundler-questions/