Give me some light please

1. On the main page there is "OctaneRender 4™ Enterprise for CINEMA 4D® is available for the following:
Windows Vista, 7, 8, 8.1, and 10 – (R13 – R20)"
In demo folder I can see only r15+ versions. Where can i find r13 demo file ? Will full version work on r13?
2. So.... No free version for C4D up to two GPUs? I think I was also not advertised enough, because I was pretty sure it will work that way...