Put the NH fluid in it. Saving $40 on 5gal of fluid isnt going to sound so good if you need to change any hard parts.
I believe that machine is hydro drive.
Hydraulic fluid dosnt have 3rd party testing like the API for engine oil. This means any oil manufacturer can state anything on the jug and no ones checking it.
I should state that I do use off brand fluid in things that don't have hydro drive, wet clutches or wet brakes. I also use it in things like log splitters. Just not for something expensive.