Customise Wordpress (Woocommerce) Plugin

[Overview]
The site is installed with B2B Sales Agent Portal, it's a plugin to add Sales Agent into a typical WooCommerce site (with only customers), with the ability to let the Sales Agent add their own customers, submit orders on behalf of them, and get commissions through the sales:
https://woocommerce-b2b.com/sales-agents/

[Points]
- The sales agent can access to the Sales Agent Portal, where they can see their customers, sales, commissions, etc.
- Sales agents can invite others to join as sales agent, through the backend, Admin will create the new sales agent user, and set a custom field to link it to his referral.
- The custom field is created using the "Advanced Custom Fields" plugin (User field type):
https://www.advancedcustomfields.com/
- The first sales agent will be the team leader, so the referral custom field will be empty.
- All sales agent with the custom field empty means they are not referred by someone, and considered a team leader.

[Requirements]
1. To create a custom page in the Sales Agent Portal, where agent can view the a tree chart of his team, and the total sales that his team has accumulated.
2. The chart will only show sales generated for that same month.
3. Please refer to the attached screenshot on what's the expected results. Through the chart, the sales agent should be able to see sales made by each sales agent, and the total sales of all.
4. At the backend, Admin can view the same chart (like the sales agent). In addition, Admin can select a team/user to view (while Sales agent can only view the team they're in), and filter the data through different months.