I know budgets are tight. If you search Google or Reddit (r/LearnJapanese), you will find links to shared Google Drives and illegal uploads.
If you have finished Minna no Nihongo I & II (the Shokyu / Beginner series), congratulations! You are officially at an N5 and N4 level. minna no nihongo n4 book pdf
You won't find a perfect "Minna no Nihongo N4 PDF" because the book doesn't exist under that name. You need the book. I know budgets are tight
My advice? Try the first. If you love the layout, buy it legally. If you just need grammar points to pass the test, use the free websites above. use the free websites above.