The source is irrelevant. If you didn't make it, take it, design it, construct it, or buy the rights to it , you do not own it and cannot use it. Since you are asking some red flags must have popped up. Listen to them and only use original materials or materials you have permission from the artist to use. Just because it's on the Internet does not mean its by default public domain. That is a common and misguided notion.
Best of luck and remember the artist deserves compensation for their work just like you deserve compensation for your work.