RTIR 3.2.0 is the first release of RTIR compatible with RT 4.2.
It is only compatible with RT 4.2.9 and later and will refuse to install on earlier versions of RT 4.2.
You should be sure to review both core RT's UPGRADING-4.2 as well as RTIR's UPGRADING-3.2 documentation and any other UPGRADING documentation which may be relevant to your old version.
You can find complete release notes and downloads on https://bestpractical.com/rtir/