Hello.
10 under is possible, because people have done it. You wonder how they can.
My first round was a 96, then I got a 79. Today I got a 68 (-2), would have been a 67 had I not missed one small putt on the back nine. I had five birdies. That is only my third full round. I just took my time and tried to calculate every shot. You need a bit of luck also. It's easy to mess up your whole round on the 5th. I could have got a birdie there, but ended up with a bogey, which I was happy to get. That hole really messed up my first round, everything went downhill after that.
I really hated the course after my first round. The second round I was happy with. Now I quite like the course. You have to think carefully about every shot, know when you can use the driver and when you have to play safe. You need to think your way round the course.
Keep playing it and you will see it is possible to get a low score.