Yes these characters are marked as Royalty Free, which means you can use them without a copyright issue as long as its used as intended such as a video game/film etc.
Guidelines for Royalty Free Usage:
https://www.cgtrader.com/pages/terms-and-conditions#general-terms-of-licensing
You can always contact the artist before you purchase if you want to double-check with them about details.
What I said about requesting your money back - if you have purchased a royalty free model and then find out it has been licensed incorrectly then you can ask CGTrader for your money back. Most people try to do the right thing however people do make mistakes and what not.