Should i use drupal to create this web application? [on hold]

I have requirements to create a website with the following features:

1. Will have some static pages that can be browsed anonymously (no login required).
2. Some pages will require that a user be logged in, as they show content private to that user
3. It is possible that user authentication may need to be against an external system (e.g, LDAP), instead of a database table. But this will depend on requirements.
4. Users shall be presented a registration form to create an account for themselves. But accounts for users can also be created by an administrative user in the back-office
5. There are some user interactions on the site that will cause data to be fetched from an external web API. This data will need to be stored in database, to be used later.
6. A logged-in user is given some personal space where he can upload some files (sort of an online file manager).
7. Will have mainly 2 sections: normal users section and administration section.
8. Administration section will provide mainly a CRUD interface using html forms, so that admins can have a 'back-office'. E.g, an admin will be presented an interface to add a 'Company' by filling in details, or edit/delete the record for a company. Or add/edit/delete infos about the external APIs that are consumed by certain features of the site.
9. Admins can be restricted in what they are able to do. E.g, some admins will be able to create other admin users, while others will not be able.

I have never used a CMS before. I am mostly familiar with coding a website using html, css and js for front-end, with php and an sql database.

I was wondering how much code do I have to write (if any) to create a website as described above, if i opt to use drupal 8. In particular, I am interested to know if i will be able to develop features faster than building a solution from scratch, because from scratch i will need to implement features like user login/registration, create an admin section with all the CRUD forms and admin permissions management.