Once you name your business in the first step while adding a business in DotcomPal, it creates a sub domain for it automatically according to the name. Now, if you do not own a domain and want to run your business on DotcomPal sub domain, you can proceed with the automatically generated sub domain for your business.
But in case, if you want to change the automatically generated sub domain to any other phrase, you can do that. It is not mandatory, it totally depends on your choice.
One thing is here which needs your attention that you can change the sub domain only once, so we suggest you phrase it carefully.