How to pass post api in Power BI?

Hello everyone,n

I am a total newbie to this interface of power BI, at my company a rerst api is used with Tableau Web connector to retrieve some information from a website and then tableau sent back this data into the right format

As it is not possible to use this connector into Power Query, I am working on a POC, and I needed to build a post api, so this is the information I have from my services, in tableau the user can modified a few parameters

This is the webservice I have to use: https://mywebsite.com/api/queries (it is a POST)

The user can select some filter like data and country and add the parameters they would like to retrieve

For example this selection will return the following requerst payload:
[{query: "stack(ts2mat(3,"2000","2022"), "country", ["AT"])", env: {freq: "A"}}]

I tried to follow the following guide, but I'm not able to achieve this, I think I'm doing something wrong with my request payload

Any steps to achieve this step?

Many thanks in advance for your help