You need to have MultiTerm or Trados Studio (2009 or later) installed on your machine, if you want to write sdltb files. You can read them without any 3rd party software required.
You need to have Trados Studio (2017 or later) installed on your machine, if you want to read or write sdltm files
If you want to read or write ODS spreadsheets, you need LibreOffice or OpenOffice. For these, only the 32 bit versions work, not the 64 bit releases.
Created with the Personal Edition of HelpNDoc: Benefits of a Help Authoring Tool