I don't use Mac, but the card reader should work. It is simpler and more controllable than connecting the camera to the computer and using an automatic upload.
Can your computer see the files on the card? I would go to My Computer on a PC. I assume you have an equivalent on Mac.
I just open the card in a small window, then I select and drag all the image files out of the card and drop them into a folder made for that batch of pictures. I name the folder for each batch something with a date and description (2016-02-04; arboretum) and that way you don't have to fool with anything and you control where the photos are going.
We don't have enough information.
OS X 10.6.8 is pretty old (Mac is now on OS X 10.11.3). What software on you using on this Mac to import (or to try to import) the images?
What card reader are you using? (Brand & Model).
I used Mac OS X since 10.2 and I've been through several different brands of card readers, USB hubs, etc. and I find that there's a lot of flakey unreliable hubs and readers out there. For this reason, if you are going to connect the camera to the computer via the USB cable then I suggest you use the USB cable that came with the camera. You must be especially careful that you're not using a "USB charging cable" that sometimes accompanies devices that use a USB cable excluseivly for charging batteries because I've encountered a few of these where the data pins aren't even connected -- so there's no chance those cables could work. The Canon camera uses ONLY the data pins (it doesn't use the USB cable to charge the camera).
Avoid using a USB "hub" -- use direct connection. I've found a few reliable hubs, but I think I find 2-3 flakey hubs on the market for every quality reliable hub I've encountered. I've gotten especially fussy about which USB hubs I'm willing to use (my favorite hub was discontinued or I'd offer a recommendation.)
As for card readers... there is only ONE card reader I've encountered that has literally worked on every Mac and every OS version that I've ever tested. It's the "Lexar Professional USB 3.0 Dual-Slot Reader" (list price is about $48 -- Amazon sells it for about $30). Every other reader I've used would either not work at all, or work for a while then quit... or work until I upgraded the OS and then not work again, etc. I just got sick of rolling the dice on which card reader may or may not work -- so this is now the only card reader that I recommend.
But getting back to software...
There are numerous programs on a Mac that can import images direct from the camera. iPhoto probably came with your Mac and that works. Adobe Lightroom can also import from the camera. I previously used Apple Aperture (but have since converted to Lightroom -- Apple no longer intends to do further development of Aperture).
The Mac can be configured to auto-launch a photo program when it sees a camera or camera's memory card connected... and there are multiple ways to configure this. But even if it's not configured, you should be able to manually launch an application and import the images.
The next question is... once the card or camera are connected... does the Mac know the device is connected (is this a problem with the device being recognized by the Mac... or the device is recognized but you're uncertain how to transfer the images?
I wrote up instructions on how to use the Mac's System Information utility to determine if the computer can recognize the camera connection. You'll find that here: