You can password protect a folder in Windows 10 using a program called WinRar, which is free to download and use.
You don't have to spend a cent to secure your documents and other important data. Use trusted free apps to lock everything down and send it safely to anyone. If you want to keep your files private, ...
To password protect a PDF in Adobe Acrobat Reader, you'll need the paid Pro version, which starts at $14.99 a month.