I am sorry for the troubles. Once the download process reaches 50% it begins the process of transferring the files to the SD card. Please see the suggestions in the FAQ: Why does my Downloadable Content freeze at 50%?
If you continue to have troubles please contact Garmin Product Support by phone.
Trying for the 7th time now. Again stuck at 50%. has been sat for 2 hours. Not impressed with Garmin at all. It is not loading onto the SD card at all. Have done everything on the list to no avail.
If you have made sure that the SD card is not locked, used a separate card reader to download the mapping to, and tried a different browser and the downloadable map still hangs at 50%, you need to contact Product Support by phone for further assistance.