I am using an Olympus E420 and as I wrote in the title, I seem to be missing profiles in Camera Calibrations section.
That camera model was profiled prior to the days when Adobe started creating Camera matching profiles. So Adobe only has the Adobe Standard profile which is specific for your camera model.
The other ACR 4.5 is the initial profile when support was first introduced by LR & ACR. Support was added when Adobe Camera Raw 4.5 was version.
What a pity - that is what I thought - thank you for answering my question!