I would say best to call customer support and get them assist you
Also post what product you have and the Operating system and service pack. Each product has its own retail card activation FAQ and things appear to have got messed up somewhat.
The below is what should have been done
You can use the below links to activate the corresponding McAfee product using the Key provided. Alter your country using the drop-down menu accordingly.
http://www.mcafee.com/mtp/retailcard (McAfee Total Protection)
http://www.mcafee.com/mis/retailcard (McAfee Internet Security Suite)
http://www.mcafee.com/mav/retailcard (McAfee Antivirus Plus)
Once you activated the product you can use the below instruction to login to McAfee account and install the products.
or for the RetailCD version:
http://www.mcafee.com/mav/retailcd for mcafee virus scan plus
Redeemed the product key. Log in if you have an existing account with mcafee if not click register now.
Do the onscreen prompt to download/ install.
I assume that you are referring to the Download/Install process. I would suggest to do the below steps and see if that helps..!
1. Restart the computer and start Run dialogue - Win key + R
2. Type in temp and hit Enter. Select all files present in temp folder and delete them.
3. Type in %temp% and hit Enter. Select all files present in the folder and delete them.
4. Open your web browser and login to https://home.mcafee.com using your Email and password.
5. Click on My Account and download the McAfee Installer setup file (Make sure that you notice the location where it downloads)
6. Run the downloaded file and once it prompts for Serial key , copy paste the key given in Download page of the Installer file.
Check to see if Install progress.