There are several ways to import materials from Chaos Cosmos to Revit.

Use the Import button to add Cosmos Browser Materials to the V-Ray Asset Editor Materials list.

Use the Import Options button to enable the triplanar mapping function for the selected material. This feature automatically scales materials to their actual size taking into account the scene units.

Imported materials appear in the V-Ray Asset Editor in Revit. Assign them as material replacement in order to see them rendered.

You can also apply materials directly by dragging them into the Appearance Manager's Materials and Global Overrides tabs. Materials can also be applied on the edited Cosmos assets from ||Appearance Manager|| > Families tab > Cosmos sub-tab.

You can also drag and drop materials into the Settings panel > Environment tab > Infinite Ground Plane section > Material slot.