The issue is that RAID creates an array and presents it is a logical storage device to the OS. The OS does not know what drives make up the array. Even though you have two Intel SSDs, the installer cannot know that and only sees some storage array that is not explicitly Intel SSDs.
There are other free ghosting/imaging programs out there as well.
The RST is basically 3rd party software for your specific storage controller. It basically knows how to access information from the controller better. The OS itself cannot so the Data Migration Tool (license from Acronis) cannot either since it uses OS information during installation.
Again, there are free 3rd party migration/imaging/ghosting/backup software out there. However, always backup your data before attempting any migration.