HI Jane721 
please can someone tell me where exactly it should be installed?
Q: Where have you installed the genesis starter essentials to,.. ?
As Richard says, it’s Normally Users / MyDocuments / Daz3D / MyLibrary
Daz Studio should create that folder when you install it,. and the Genesis Starter essentials should automatically be installed into the My Library folder,... Unless you specified some other location.
If you’ve installed all your content to a Different location EG: F:/ My Daz stuff,... then this add-on product would need to be installed there.
The product is looking for the genesis morphs, and if they’re not in the location you’re installing it to,., it won’t install.
If you open Daz Studio,. then go to EDIT / Preferences .. then click on the Content library tab, ... then the content directory manager button. ... then open up the Daz Studio Formats list by clicking the little white arrow… so you can see the list of mapped locations…
if you can post a screen shot of that,. we can help more.
PIC to help
Click thumbnail to see full-size image