Whatever happens, please post the solution to help others.

Low fluid makes pumps buzz due to cavitation ( air bubbles / pockets of vacuum that open then collapse. ) In the near term the pump won't be damaged and won't need to be changed.

Checking the fluid is more involved, if you don't have a way to lift the car level it will have to go to a shop. I " think" this trans was also used in Chrysler products so a good domestic shop should be able to help.

Doing some searching, this trans has a standpipe in the pan and what looks like a drain plug but really isn't. The trans is run to a specific temperature ,plug removed. If a slight bit of fluid dribbles out, the level is good. To add fluid it must be pumped through the standpipe plug. Get creative here, turkey baster, tip from a gear lube bottle screwed on the trans fluid bottle. ( Might not work with MB factory fluid / some large cap USA bottles )

There is apparently an uprated pan ( +3 mm deeper sump , taller stand pipe for more fluid )

Regardless the pan should come off the trans at some point for a look and fluid change