During the install process of Zen 1.5 you are forced to rename admin. Otherwise it won't let you log in. So, everybody's admin folder has a different name. That's why you need to change the folder name before uploading.

So, for instance when you log in to Zen Cart what URL do you use? It could be something like:

www.mydomain.com/office

or

www.mydomain.com/ehfbfvbv

The second bit of that is the name of the admin folder. So, for example 'office' or 'ehfbfvbv' . You have chosen that yourself during the installation process. So you just need to rename the YOUR_ADMIN folder in the package to that name before uploading it.

Once you have downloaded the package you'll have a folder. In that folder there is another folder called 'Installation Files' . In that folder you should have:

--bmz_cache
--images
--includes
--YOUR_ADMIN

That is the your admin directory that you need to rename.