Minna no Nihongo honsatsu remains a core resource; romaji supplements can help beginners but should be phased out. For any 2021 PDF or specific "16" edition claim, verify via official publisher or library sources and avoid unauthorized downloads.
If you want, I can:
Some university libraries and major city libraries (especially in Asia, Europe, and North America) carry Minna no Nihongo. You can borrow and scan chapters legally. minna no nihongo honsatsu romaji pdf 16 2021
If you buy the physical Romaji textbook legally, you can scan it into a PDF for personal, non-distributed use under fair use laws in many countries. This gives you exactly what you need: a personal digital copy of the 16th printing (2021). Use audio resources (CDs, streaming) from official materials