The gearbox itself is the same 6 speed as fitted in cars with a manual shift/clutch pedal. It has the same drain and fill plugs.
If you want to check the SMG pump reservoir level then this is located on the side of the gearbox.
Link to TIS info :
https://www.newtis.info/tisv2/a/en/e85-z4-2.5i-roa/repair-manuals/23-manual-gearbox/23-42-hydraulic-add-on-parts-smg/EERN5Ly