Every company has its own rules, although many of them are unreasonable. As you said, your company doesn't allow employees to post calligraphy works on the wall. Don't get angry, just get used to it, do what you say, abide by company regulations, and post it as a manager. You can see who will say what about you. So now you just have to work hard and try to climb up!
I hope my answer can help you! Hope to adopt!