Dual Booting: How in god's name?!

I have one drive, 1tb with Pop_OS, and another, 500 on to which i want to install windows. (I know, I dont like it either but I want to play VR games via link cable cause ALVR is really mid) So, I put the ISO on a drive with ventoy, booted it up, got it all going. started to install windows on the empty drive. So, after the five...