You are trying to run an mkfs command. But you get "mkfs unable to open device /dev/nvme device or resource busy". What should you do?
Are you 100% sure the target of the mkfs command is the one you want?
The target may be /dev/mapper/nvmeABC123 for example. Try to ascertain the destination (often the last argument) of the mkfs command. Is it really /dev/mapper/nvmeABC123? You may want to try rebooting the server. If you are following directions, there may be a mistake in the directions.