VAPT assessment and security certificate (PHP)

I have a support website www.support.sampledomain.com. The website is in PHP and has pages like login, forget and reset the password, create and update incidents, create and update documents, manage users, manage profiles, and manage lookups.

My main objective is to get a security certificate. Therefore, in addition to providing report, any pointers to obtain security certificate will be helpful.

NOTE: I cannot share any developer related password like FTP, CPanel, etc.