You should always acknowledge content that isn't yours. Even then, just copying content from elsewhere on the web can attract flags - just not as many as if you try to pass it off as your own.
Whatever you might have been told about steemit, people here react best to original work. If you try to misuse the system, you will attract the wrong sort of attention - you can loose post rewards and your account's reputation.
Thanks for For your clarification.
I'll remove my flag - for now. I will come back to check up on you though. If I catch you using someone else's work without properly linking to it again, it will not be pretty.