Power BI Reporting Solution design

Up until now I've only ever created SQL databases / Views etc that you connect to in Power BI and create your own simple reports. I've populated data using Azure Data factory and or SSIS.

I think the below solution is a little more complex so the model when imported has all the joins already configured and the tables and field names are are clear and obvious to the Report developers.

My questions / assumptions are in brackets ()

My task is to present design that full fills the below requirements.

Project: Create reports using Power BI

Source is single Azure SQL DB (very small sales data about 15 tables or less).

Design:-

Design a solution using Microsoft Azure to ETL/ELT, stage, model. (What is this exactly? Are they referring to "tabular data models" ?)

Output:-

Provide solution using above as in input to Power BI so users can create their own reports. (What data source is the input?)

Data is Sales related so need to be able to restrict users to their own sales region data.

Senior management though can see everything.

What's the best way to apply security to to Azure Data?