The web design packages are for use with UltimateWB software, so you would not be using Joomla for content management anymore, but your UltimateWB website admin panel. It is fine that you would like to use your own domain name and web hosting that you already have, as long as your web hosting allows for UltimateWB software to be installed on it (i.e. you are allowed to upload files to your web hosting account), and that it satisfies the server requirements as listed on the server requirements page at https://www.ultimatewb.com/server-requirements . Which web hosting are you using?
In regards to how we would deliver the web design to you, we would create the website for you on your web hosting, and you can then manage your website via your UltimateWB website admin panel.
Please note that your purchase would then require UltimateWB software as well, possibly just the Lite version, if you just want a basic website with a contact form, vs. social networking/e-commerce features. You can compare the 3 versions of UltimateWB software in the comparison chart here: https://www.ultimatewb.com/compare-uwb .
Also, if you will be using your own web hosting, you will either need to install your purchased software onto, or purchase the installation service add-on at https://www.ultimatewb.com/pro-services . We do provide instructions/video tutorial on installing the software on your server at https://www.ultimatewb.com/installation , and also do provide free tech support. Please note that all of our UltimateWB web hosting packages do come with free professional installation of your purchased software onto your server (still requires separate purchase of the software though). You can check out our UltimateWB web hosting packages here: https://www.ultimatewb.com/domain-names-web-hosting .