ExportToFile how to use repotLevelFilter example

Hello,

using rest api to generate PDF from power bi report. 

my body is:

{
  "format": "PDF",
  "powerBIReportConfiguration": {
    "pages": [
      { "pageName": "9239c7e57318c00529b1" },  // Datamart
      { "pageName": "4e4e3e8bbb5003f74890" },  // Azure NetApp Files
      { "pageName": "c0d90322bab9ebf29cc8" },  // Version
      { "pageName": "371102698be09cb104a6" }   // Budgets Daily
    ],
   "reportLevelFilters": [
  {
    "filter": "Dim_EA_Classification_BudgetEvaluations/Category eq 'CCHBC AA Lab/Advanced Analytics/Data Platforms'"
  }
]
  }
}

PDF is successfully generated, but there is no filter applied. 
Can anybody explain in simple terms how can i Use this filter? 

Why this is not working? If this is a wrong syntax?

And this is per report or per table? 

And one more bonus question:

If i can set up filter on table data, what about slicers? How to make them be filtered by a specific value? It is possible by ExportToFile?

Best,
Jacek

Best,
Jacek