With DroboAccess/myDrobo you don’t need your own certs - myDrobo takes care of that for you and gets its own certs for the mydrobo.com domain you chose.
DroboAccess is fundamentally based on ownCloud, although it doesn’t have all features enabled. A lot of work was done on DroboAccess to make it very easy to use/install
So, unless there is something specific you need from ownCloud that DroboAccess doesn’t provide, I would encourage you to look at DroboAccess.
I thoroughly agree DroboAccess is far from OwnCloud. I bought the Drobo 5N (already had a 2nd Gen) because I wanted the apps. And I am very disappointed to see it is running old version of OwnCloud and attempts to update past 8.2.1 are failing. I want to use it to share pictures and videos with family members and have them add their own pictures and videos as well.