Using the M.2 NVME slot to dual boot the Khadas Edge with Captain board

Dear Mr. Gouwa:
I have the Khadas Edge with the Captain board and I can run Android from the onboard EMMC memory on the Edge. I would like to setup a dual boot system and run Ubuntu from the M.2 NVME on the bottom of the Captain board. Could you please send me instructions to install Ubuntu on the M.2 drive.