[Help] TNAS F4-210 And Domain issues

[archiplus]

As far as I can see my NAS model TNAS F4-210, with 4 8tb HDD's con not be registered on a Windows Server. Is thst right?, and If so, Soes nayone know how to work arround this issue? I mean if it is posible to manyally create the users on the TNAS ussing their name (previous for win 2000) without the @domain.local?
Many thanks for any help you can provide