Hi I've bought some products from Flink and they come with a folder named Daz4materials (with some variations). Where do I put those files in "My DAZ 3D library" folder. And second. Where do I find them in my Content Library Pane?

https://www.renderosity.com/mod/bcs/?ViewProduct=110308 https://www.renderosity.com/mod/bcs/?ViewProduct=108890 https://www.renderosity.com/mod/bcs/?ViewProduct=93679

There's probably no required place you have to put them; you could create a folder under Props and put the materials there. You could also load those props individually, apply the materials and save them back to the directory you created as a Scene Subset, so you can load them easily back into your scene rather than trying to find them from the runtime directory that they are currently saved from.

Judging from the website readme files, those mat folders go directly into the content Library. In DAZStudio, go directly to the Content Library tab and make sure that the My DAZ 3D Library folder hierarchy is expanded; there you should see the appropriately labeled presets folders for the Flink props.