Get a file from the site on demand

It is required to create a php script to retrieve data from the site by the specified argument. Actually make an api get data through a GET request.

In other words, the source site has a search string input field and a Submit button. Clicking this button returns a page with text information and a Download File button. When you click the Download File button, the site returns a text file.

I would like to automate the process and get the file immediately through a GET request. It is advisable to use php to create this api.

The desired site and details are ready to provide in private messages.