Mantra theme with WP e commerce plug in: user's cant register

Hello, and thanks for all the hard work on the Mantra theme. Its really great. I am having an issue I was hoping you could help me with.

I’m using Mantra and WP E Commerce to run an online store. My problem is that customers can’t create an account or complete checkout without creating an account. Ideally I’d like them not to have to create an account in order to checkout, but to have the option to do so if they would like.

The testing version of the site is located here:

https://www.shoekahuna.com/shoekahuna/

If I need to provide any further information please let me know and thanks in advance. This is my first time using either Mantra or WP E Commerce, although I have successfully developed quite a few sites using a variety of other themes and plug ins. The WP E Commerce plug in is required as my customer wished to integrate to Quickbooks via Webgility. WPEC is the only option available for that.

Again many thanks,

~ PixelCraft