Older version of R in mac OS X 10.10.5

I have a problem downloading R in my mac which I have been dealing with for many hours now.

My purpose is to use propensity score matching in SPSS (from source forge). I am using SPSS version 22 on my mac OS X yosemite 10.10.5.

After reading a lot on the different sites I need to use R.2.15 for SPSS 22 in order to use the psmatching 3.03 on source forge.

However, I cannot seem to install R 2.15 when I run the installation package. When I am going to select destination on the macintosh HD, it says that R2.15.0 for Mac OS X 10.5 or higher can’t be installed on this disk. How is this possible? My OS X version is higher than the demanded version for R 2.15.

Any ideas how to make the installation?