To clarify: OpenSprinkler generation 1 (1.x) is compatible with NanodeRF, because 1.x uses ATmega328 microcontroller and has PCB slot for RFM12B. All the pin assignments are also compatible with NanodeRF. Generation 2 (2.x) has switched to use ATmega644, so that’s not compatible with NanodeRF any more.
If you are using the Virtualbox Image, you should be able to compile 1.x source code within the size limit. Do you have a screenshot so I can perhaps see what may be wrong?