Sharepoint solution for a case management

We are a charity organisation that help people with their housing related issues.

We need to transition to the microsoft ecosystem. And I am technical savvy but not familiar with that.

I want a proposal for how to achieve the following:

public facing webform with address field, questions, and PDFs upload (no login required, should be public)
if submitted:
- new entry in the client table with personal information
- create a case, with link to the pdfs
- alert to me

In addition, I want to see the overview of the case.
There are two case type: one time contribution and credit (needs to be paid back)
The files need to be linked
There are different status : pending, approved, paid, closed
For the credits, we want to have an alarm for the beginning and end of the pay back time.

Again, I want to have a detailed plan how to implement this (which add-on, how they interface, data models, what needs programming).

Implementation is a second step.