In this case you will need to re-format your drives or consider the option to re-create the RAID array that you have because the fact that is showing 0 GB as available size could be related to storage availability or a RAID corruption and since it is a RAID 0 there is no recovery option so you may need to create the RAID again.
Can you please provide us with the exact Windows 10 version that you are trying to install? Also you will need to confirm if the computer that you have supports Windows 10. For that you will need to contact Dell so they can give you that information. You can also check the support page of your product on the following link: http://www.dell.com/support/home/us/en/19/product-support/product/xps-8300
If you need more assistance please let me know.