Go to your steam app and find your library with GTA V and right click and go down to "properties" and select the tab "updates". If updated successfully you need to go back into your GTA V folder and right click on the GTAV icon to properties and click details to make sure you are on the v573. Also like DCP1293 stated make sure you are now updated to the new release of RPH.
I am currently having issues as well with the new update crashing and getting a BLANK disclaimer window and then crashes. Maybe a few bugs still left to work out.