APEXII should check the normal paths for saint. See if you have a c:\saxi directory or try doing a search for saint.exe. In windows I think it is installed as part of the Bruker-executables packe? It could also live in c:\bn\saxi from memory. In Linux it is found in /usr/local/saint and comes as an rpm.
I do not have a copy of saint as I use Linux exclusively now and even if I did I could not provide you with one as it is licensed software.
Open source is the way forward. I'm sure Bruker could provide new executables to setup your machine if you have lost or had to replace them. You will need to register with their website portal thing (good luck with that).
Reading your previous post about .kcd files if you processing data off a Kappa then you may actually be using evalccd or hkl2000 (denzo-smn) and those may be present instead of saint?