My name is Lennart. I started CC0 Textures in January of 2018 because I was frustrated with the limitations of most texture sites. Thanks to some support from HdriHaven the site has grown quite substantially, it now generates has more than 1.5 million downloads per year.
Every material can be downloaded instantly and without any registration or restrictions. The materials come in resolutions of up to 8K (or even bigger in some special cases) and many of them even come with SBSAR files so that you can adjust their parameters using the Substance Player.
If you have questions or want to report a problem you can do so via twitter (@cc0textures ) or via mail to hello[at]cc0textures.com.