Unlimited Download center can be considered a safe site to use, as long as you take precautions such as using an antivirus program and not clicking on ads or popups. However, because it is a third-party site, there is always a risk of malware or other security threats.
Legality
As far as legality goes, Unlimited Download Center falls into a gray area. Some of the content available on the site may be copyrighted, and downloading and distributing it without permission could be considered illegal. It's important to research the legality of any content before you download it, and to only use the site responsibly.
Overall, Unlimited Download Center can be a useful site for downloading a variety of content. However, it's important to be aware of the potential risks and to use it with caution.