1. The administrators will create the users (customers)
This could be done with CRED User Forms.
You can create Forms that add new users. If the Admin who creates those users has the Email, name and so on of the users, he can do that himself, and the notification system of CRED will help to send notifications to the new users.
Also, the Visitor (prospect) can create the new user himself, by using the same form.
The DOC for this is here:
https://toolset.com/documentation/user-guides/cred-user-forms/
https://toolset.com/documentation/user-guides/cred-user-forms-email-notifications/
If you need specific Help with CRED User forms, please ask for it in a singular Ticket, so we can keep all issues separated and on the topic.
2. Each customer will have his area where to download pdf’s and other documents that the administrators will upload to each client’s area.
This is a little tricky.
WordPress does not provide a Front End Profile, and neither does Toolset.
What you can use here is either several user Fields, where you (the visitor or the admin) can upload several things to the User Profile itself.
This User Data can then be displayed with Toolset as an example on a Page, where the current logged in user information is displayed.
That means, also a file (uploaded to the particular logged in user) would be visible there, and only visible to the given user.
An email notification can be sent with the same principles as in the DOC above linked elaborated.
Here is elaborated how to create and display User Fields:
https://toolset.com/documentation/user-guides/user-fields/
https://toolset.com/documentation/user-guides/displaying-wordpress-user-fields/
Also here, if you need specific on topic info or help, a separate ticket would be the way to go
3. Every time an administrator uploads information, the system will have to send an email to the customer advising that he has new documents to download.
This can be done as above mentioned, by sending an email to the User when the Edit User Form is submitted.
You can also trigger this Email only if some Fields are edited.
The details are in the DOC above linked, here again for reference:
https://toolset.com/documentation/user-guides/cred-user-forms-email-notifications/
4. On the other hand, customers will have to be able to upload invoices or other documents in pdf to their customer area and then, the system will have to send an email advising the administrator that customer “x” has uploaded files to his area.
This is possible in the same way, it just needs a second User Edit Form, that the user will use when editing his profile (uploading the data)
In CRED there is a particular Email setting "Send notification to a WordPress user:", where you can define the User to receive the notification, in your case this will be the Site's Admin.
