Hubertus was (still is?) a Retailer of outdoor/sporting/hunting/shooting equipment. They've been in biz since before WW2 at least.
Same type of retailer as AKAH, GECO, etc.
AFAIK they were still in business in the 80's.
(St. Hubertus is the patron Saint of Hunters)
Some of the sniper scopes supplied to the German forces in WW2 were marked Hubertus being sourced from them.
The 'scopes were made for them by prime optics makers. Sometimes those makers marks are on the scope, sometimes not.
Someone with a lot more knowledge about optics can likely tell you when that particular model was mfg (Pre-War or Post-War) and who the actual mfgr was.
That's what I have been told about the name.
Right now, Kreighoff uses the Hubertus name as a Model designation for a high dollar single shot hunting rifle.