1. I assume you're using the Microsoft Creation Tool with the Win 10 Setup files to fresh-install the OS onto your brand-new "virgin" (unpartitioned, unformatted) HDD. Please confirm that for me.
2. During the beginning of the Win 10 Setup process, following your selection of a "Custom" (fresh) install of the OS, Windows Setup will ask "Where do you want to install Windows?"
3. Your brand-new "virgin" (unpartitioned, unformatted) HDD should be listed indicating its total size (disk-space) as "Unallocated Space" (or "Free space").
4. Ordinarily you would click Next to continue the Setup process so that the OS would be installed on the HDD (unless you desired to multi-partition the HDD, in which case you would select the "New" option to two or more partitions.)
5. So Setup should indicate your 2 TB (that's Terabytes, NOT "trilabytes") has about 1,862 GB of unallocated disk-space.