Extract the contents of "Content DD Diadem.zip" to the daz3d content library.

The files can be found in its respective locations within daz3d content library.

For example:

C:\Users\Public\Documents\My DAZ 3D Library\data\TarkArk\Dress Drak\DD Diadem

C:\Users\Public\Documents\My DAZ 3D Library\People\Genesis 8 Female\Accessories\TarkArk\Diadem\DD Diadem

C:\Users\Public\Documents\My DAZ 3D Library\Runtime\Textures\TarkArk\TA_Dress Drak\Diadem