Select the disk where you want to install macOS?

The specs sheet on the manufacturer's site for the Aura Pro X2 list macOS 10.13 High Sierra as the minimum compatible version.

The manufacturer recommends upgrading to macOS 10.13 High Sierra prior to installation. If that isn't possible I'd try using a USB installer for macOS 10.13 or higher as outlined here.

You are going to need to format your newly installed ssd before the macos installer recognizes it as a viable medium to install your os on. If you cant format it in disk utility, try going to internet recovery and selecting the terminal. once in the terminal type

diskutil list

Then find the your newly installed disk drive labeled in the format of /dev/diskXwhere "X" is whatever disk number your new ssd is. This will most likely be /dev/disk0 or /dev/disk1.

Once you have identified your disk number in the terminal, you can erase and format your new sdd by running the command

diskutil eraseDisk apfs MacHD GPT /dev/diskX

Dont forget to substitute the "X" in "/dev/diskX" with your real disk number.

For example, if your new ssd shows up in the terminal as /dev/disk0, the command to properly format it would be:

diskutil eraseDisk apfs MacHD GPT /dev/disk0

After that your new ssd should show up as an option in the mac installer application and you should be able to install macOS on it.