I just finished doing this a few minutes ago and I had better luck. I left my drives plugged in. Booted to mint USB. Made sure I knew which drive was the empty one using the Disks app. Ran the installer and chose the option to erase disk instead of alongside. Set my BIOS to boot from new disk, and grub let’s me choose between windows and Linux.
My laptop on the other hand, was not a good time. It shipped using the raid controller, so mint couldn’t see the second drive. And windows freaked out at the change of disk controller and I couldn’t recover. 2 operating system installs for the price of one 🫠