I got on the telephone and talked to one of the Bobcat team members at Garmin. "We" did in fact upload to my GPS the map sample that the BiCiMapas retailer sent me, that I had loaded on my Macintosh computer.
So, this is how it worked. The retailer sent me an attachment of a GPS map originally created in PC Windows format, that he converted using MapConverter into a Macintosh compatible format. I was able to open the attachment, load it to my Macintosh, find it in Bobcat and finally upload the sample map in the Garmin GPS device using MapInstall. I Love it!!!!!
The Garmin Macintosh team guy also said that preloaded maps on SD cards can't be converted to a Macintosh format. Don't need this more expensive option, even if it worked, now that I know that the download process works.