I have to tell you the truth that no freeware can help you do cross-platform USB drive encryption.
You must know that the Windows BitLocker encryption method is not available on Mac while APFS (Encrypted) is only macOS-supported. So, you have to get assistance from a third-party tool to help you encrypt your USB for cross-platform Windows and macOS use.
You can choose the best USB drive encryption software - iBoysoft BitLocker for Mac. This utility can help you encrypt your USB drive with the BitLocker encryption method on Mac. And with this tool, you can unlock and access and edit files on the BitLocker-encrypted USB on your Mac as well.
Here's how to use iBoysoft BitLocker for Mac to encrypt a USB with BitLocker on Mac:
- Connect your USB drive to your Mac.
- Free download, install, and open iBoysoft BitLocker for Mac.
- Click "Encrypt" on the app's toolbar.
- Select the partition that you want to encrypt.
- Click "Encrypt".
- Enter a password and save the BitLocker recovery key.
- Wait for the encryption process to finish.
Now, you can use the BitLocker-encrypted USB drive on your Mac and Windows PC seamlessly.