Update: The Kraken2 data manager was just released today. Please give it a test run if you still want to use it:
https://toolshed.g2.bx.psu.edu/view/iuc/data_manager_build_kraken2_database/e4cdf82de430
We’ll be adding the full Kraken2 tool suite to Galaxy Main soon, with indexes, if all works out as planned. Expect other usegalaxy.* servers will do the same.