Unzip or Unrar the internal DyadSystem 2025 directory anywhere.
Make a directory on c: (or wherever you prefer) called DyadSystem
Open the DyadSystem 2025 directory and copy the contents to the c:\DyadSystem directory.
If you have changed the name of the directory containing DyadSystem, you must edit the DyadSystemProlog32.bat file and change the directory name to the one you have chosen.
For example, if you have placed the DyadSystem in f:\programs\audio\DyadSystem
you change the bat file to 
   cd f:\programs\audio\DyadSystem\ArityProlog32\bin
   call api32

You then make a link to the .bat file and put it on your desktop for convenience.