need wordpress or codeigniter theme . paid members and admin share file and messages

I have one website requirement. One international registered company. They provide standards certificates (Like ISO) and Standardization training.


1, online register for Subscribers

2, Pay online payment gateway in Paypal

3, Subscriptions renewal option

4, Subscribers and admin need upload and download some files and messages to admin panel also send company email

5, Admin need provide certificate to subscribers (printable or download). Have certificate image.

6, Admin want block or other common features etc…

7, Users need other common features (like password forget or change… etc)

I have basic PHP knowledge. Please help or advice