For omnisphere2 to work it require plugin registration and steam library folder in place.
However due to size issues its not allways possible to keep steam folder in C: Drive .
So instead a shortcut of steam folder (create shortcut to steam folder- rename it to steam) is placed to default location.
This way we can move steam folder to any drive without causing a issue to plugin.
Plugin updates are released from time to time and need no re-registration, if you already have registered previously.
Version 2.6.4c has some change in registration now it no longer offer challange code.
Easy solution to this is to register 2.6.3c and replace it with 2.6.4c.
Other issue is omnisphere plugin stays at multiple location so one need to replace at all location.
Steam (folder) file check hash will be posted some other day , with this you can check your steam folder integrity. As many times onmisphere show steam folder related error and installing steam (60+Gb )is not a very good option for most.