Windows automated backup setup?

[downloaderfan]

I'm looking to automate the backup of a particular folder on Windows 10, within which I have all my important files. I use Syncthing on my phone to backup files over local WiFi to my PC instantly whenever new files are added to a specific folder. I want a similar setup for windows, that regularly scans a particular folder for new files, backs up almost instantly & also encrypts it so that no one other than me can access it. I'm confused what hardware I should buy, like a NAS device or use an external hard drive connected to router or something else? Depending on the hardware, what software can scan for new files in a folder, encrypt & back them up for me? I don't mind paying more for a NAS device, but the advantages should also be real & not minor. (Perhaps someone could list the advantages?) Thanks