How to lock or password protect a folder on Mac mini M4?

I just checked the documentation included in the installer file. To me it appears to be an encryption utility that creates a new file when you encrypt, and likewise a new file or folder when you decrypt. Basically I would favor using a encrypted sparse image if you are needing to do this on a set of large files repeatedly. Either that or split your files into smaller groups so if you have 200GB of files you need to decrypt just so you can get access to a 1MB file that is part of the group, you aren't doing a lot of excess file processing.

To me, using a sparse image is a bit more seamless. I click on my sparse image file; I enter the password; it opens, showing a new "drive" in my sidebar which I can use as any other drive; then when I am done with my files and have closed them I "eject" the drive.

Again though, given the original statement about this computer being used by other people, the best solution is likely going to be setting up separate user accounts. Fast User Switching makes it pretty easy to switch between users.

I use File Ward…

• Functionality:
• FileWard encrypts and decrypts files and folders using a drag-and-drop interface and also offers clipboard encryption. 
• Technology:
• It's built on OpenSSL, providing robust encryption capabilities. 
• Features:
• It includes automatic compression of encrypted files and supports six different industrial-strength encryption ciphers. 

https://www.northernsoftworks.com/fileward.html

Along the lines of what muguy suggested:

Add a user or group on Mac - Apple Support

There may already be a guest account.

Each user should have their own account on the Mac. Then they will not be able to open your files.

Are you using Fileward on Sequoia? The site doesn't provide any information other than it is a "universal" binary. It then talks about OSX10.4 support which makes me wonder if the "universal" means PPC& Intel from many, many years ago, not Intel&Silicon.

Again Fileward does not say but I wonder if all it is doing is compressing the folder. If that is what it is doing, if you regularly use the folder contents and edit items then there's the risk you are repeatedly creating huge files which isn't making the best use of the computer.

Also the cleaning application for Sequoia makes me a bit leery.

I have one encrypted folder which is exclusively small TextEdit files totaling maybe a couple of MB. I store it as an encrypted sparse image bundle. After opening it with a password it creates a volume on my computer with which I can interface as i would with files on any other volume.

If it is decrypting and re-encrypting an entire folder then I would think one would see this reflected in folders and files on the computer. It may depend upon the amount and sizes of your encrypted files.

I think the easiest way to check is if it is 32 bit. ;-)

Ouch, as a matter of fact I am not certain I’ve used it on Sequoia, good question on your part. Next time I can get up & to my Mac I’ll check. How can I test for that other question?

OK, thanks.

OK, just checked FileWard is fully 64 bit, they also provide FileWard Legacy in 32 bit & runs on PPC & Intel.

I totally agree on both premises after thinking about it. 😀