Domain mapping required?

I am currently trying to create a WordPress site using a purchased template.

I am hosting my site through GoDaddy and have installed the WordPress plugin.

When trying to login to wp-admin I would be redirected to the wordpress.com login page 50% of the time.

I called GoDaddy and was told that they did not believe I needed to upgrade my domain mapping on the wordpress.com store (which I still had as I had bought it previous to using GoDaddy’s services). They believed that this may be interfering with my login.

I canceled and refunded my domain mapping and continued using the ww.wp.xz.cn login and dashboard.

About an hour into my design I was booted out of wordpress and shown an error message saying “Warning! Domain mapping upgrade for this domain not found. Please log in and go to the Domains Upgrades page of your blog to use this domain.”.

If anyone could tell me if domain mapping is required to use wordpress.org that would be appreciated.

If it is not required then why do I constantly get redirected to the wordpress.com login when trying to access wordpress.org?