As desired I did install a latest D8 and used the composer skeleton for it.
I kept the installation minimal and added only a "Recruiter" user role so that recruiter could add new job offerings. And a node type "Job" with some useful taxonomies.
Please keep in mind that a full fledged Job platform would take more than 300 days and will not be build by me in some hours.
I am quiet experienced in Drupal site building and know how to configure views, the block model, theme inheritance, display modes, paragraphs and on and on... I could easily spend hours or even days on that. Again from my perspective the stories are really vague and I full filled easily what is asked. If I now take the examples you gave and tried to rebuild those I would be lost! So what I would do is get the PO and build a prototype asap and show that to the customer to get feedback. I really believe here in "Demo or die" and building a mvp. https://www.youtube.com/watch?v=2Jhf7PcYrzY
As programming test I chose not to use webforms for the job appliance but create a module by myself and add there a simple entity and a a form by the FAPI.