Private Area Custom User Fields Profile Editing

I need to create a private area for an accounting firm for their clients. I’ve done research and this part of WordPress is a particular minefield. I used to use Contao, and all this user/protection stuff is completely built-in on that CMS. Now I’m using WordPress, so I need alternative suggestions for plugins, or how to custom write this myself.

• Custom User Fields (Company Name, VAT number, etc.)
• (possible) Registration for clients
• Login on the front-end for clients
• Private Landing Area/Page for each client, that only they can see once logged in
• Profile Editing on the front-end for clients in their protected area
• Files sharing for each client, e.g. Invoice PDFs, Tax Returns, Financial Documents, etc.
• Files/Document upload from client (with notification to site/admin)

It seems there isn’t a single way to do this. Banging head on wall.