Here is a description from the guru's installation notes for MegaMagicDreams for Omnisphere2...
BTW, you NEED to be running O2 version 2.1 or later, released late in July... If you haven't updated, you need to. Among many things, it totally simplified and redid the installation process. I assume your problem is that you haven't updated. If you're still running Omnisphere 1, google that as it is old and installing things was considered by some to be a pain in the arse... you'll need to google install procedures for Omnisphere 1 or some such verbiage. As the guru notes...
This library requires Omnisphere 2 version 2.1 or later. This update was released the second half of July, 2015. You MUST use this version of Omnisphere 2 (or later) to load the enclosed .omnisphere file! This file type is NOT SUPPORTED in earlier versions !!. This new .omnisphere file format allows 3rd party developers (like me) to save a file that has the Patch folder, the Multi folder and the Samples folder in a SINGLE FILE! You simply load this with the “Install .omnisphere” option, and it will properly place these folders/files where they belong in the STEAM folder! NO MORE SEARCHING FOR THE STEAM FOLDER! Instructions for PC or Mac: Loading the .omnisphere file: Under the Settings button, select the option to “Load .omnisphere”, (this is near the bottom of the list, between "share sounds" and Reset defaults and preferences)
navigate to the “PlugInGuru MegaMagic Dreams.omnisphere” file and load it. First will be a confirmation message about the number of patches, multis and soundsources that will be loaded. Say OK and then all of the patches, multis0 and samples will automatically be loaded into the proper locations AND you can immediately load up these new presets and play them! You can then either store/back-up the .omnisphere file or delete it. Omnisphere 2 doesn’t “look” at this file after the loading process is over. Deleting it will save you over 350MB of HD space. If you ever need this or ANY download from my site in the future, I will send you a new link for free. For now, just email me support@pluginguru.com. Installing the Bonus Presets: Every Library I sell now includes the SAME Custom Presets! NOTE: They are NOT required for any PlugInGuru Patch library to work correctly. These are custom presets that can easily set up the Envelopes, Arpeggiator or FX Racks sections of Omnisphere 1 or 2 with a custom preset which can speed up programming and open new options to you to explore. Again, you don’t have to use these – if you don’t program sounds at all then you don’t even need to load them. While the “Load .omnisphere” option automatically loads Patches/Multis and Samples, it doesn’t load these user preset files. These have to be manually placed into a specific location in the STEAM folder for them to show up in . In the past, finding the elusive STEAM folder was sometimes difficult. With Omnisphere 2 – locating this folder is a lot easier! From the start-up screen or by clicking on the Spectrasonics Logo in the Interface of Omnisphere 2, you will see a “Diagnostics” button. Click that button. Wait for your computer to count all of the patches, soundsources etc that are accessed by Omnisphere 2 (5,000+ patches!) At the bottom of the list it will say “STEAM Folder is” and show you the EXACT location of the STEAM folder that Omnisphere 2 is using If you're running the old Omnisphere and get stuck, pm me... I have many libraries with the old instructions.