Development and implementation of wordpress plugin

I entrusted the creation of a site for my project to a professional developer. I am having problems to reach the agreed product. The site consists of a platform that, by signing a subscription, offers access to various contents in written, audio and video format. All these contents are not downloadable but can only be used by the site. Access to this platform can take place by levels: the new user has the possibility to access only one free content while the user who signs the subscription can access all the contents. The contents are organized by categories. After accessing the categories, selecting a product and entering it, a page will open to present the content itself, with some information, an image and a button to access the actual content presented in writing, associated to the audio to which it refers. My request concerns a plug-in usable on Wordpress that allows me to get an introductory page without the reference elements to the chapters of the written content, as shown in the image of the example. Furthermore, the implementation of other functions and interventions on the site under construction is required. Further information will be provided to interested professionals in addition to the link of the site under construction. The work is urgent.