Is it possible to use subdomain branding?

do you have an option to use our user name as a subdomain branding for our forms?

Following guide is about exactly the one you are looking for.

https://www.jotform.com/help/144-How-to-use-Custom-Domains-with-Jotform

Please have a look at it and let us know if you are stuck somewhere or need any further assistance by our side.