You can do it easily with UltimateWB. Use the members app for the sign up, login, profile, inbox, sent box, etc., and the scrapbooks app for posting. It’s very flexible and customizable.
Got a techy/website question? Whether it’s about UltimateWB or another website builder, web hosting, or other aspects of websites, just send in your question in the “Ask David!” form. We will email you when the answer is posted on the UltimateWB “Ask David!” section.