I just went to the Ottawa library and downloaded one epub and one audio book. once downloaded to the SD card, and I hit open, Overdrive opened for both of them downloaded the content into it, ready to read.
This was incredibly easy, and as Peterhondak mentioned, go directly to overdrive to get the software there (http://http://www.overdrive.com/software/omc/AndroidEULA.aspx
After you get the software, make sure to register your ADE account in the configurations. This, was my one issue, mainly because of the archaic way Adobe handles the number of devices associated with it. I had to contact support the other night to have them reset the count, again. Even deactivating the ADE on my desktop didn't release it. I really wish they had tools in your account settings on the adobe site so you can de-authorize devices there.
the only way I could get the library epub to open in aldiko is if I download it into ADE first, then transfer the file to aldiko while the vox is connected to the PC. I couldn't just open aldiko, browse over to the overdrive folder and open it as it would give an error, which is odd considering both apps are activated with the same account. *shrug* ah well, works great in Overdrive and that's all that matters.