I rebuilt my computer last weekend with new parts (yay), and as a consequence of this I had to install Windows 10 (which I don’t like at all) because the CPU didn’t support Windows 7. Anyway, I installed the game without any problems at all. The DX install went on without any hitches, even if Windows 10 runs with DX12.
However, I had two differences from OP. 1: I installed the game on an NVMe M.2 harddisk, and 2: I had already downloaded the installer while running Windows 7 on an SSD, but unless Funcom have a different installer if you download on Windows 10 this shouldn’t have any impact.
As far as I know, Windows 12 should have all the files necessary for running applications that rely on DX9, 10, and 11 without you needing to do anything. Chances are that installing older DX versions will only make them run and finish without actually really doing anything.
This suggests to me there might be another issue somewhere on the OPs computer.
But, this is Funcom we’re talking about… 
Edit: minor spelling corrections