Unable to encrypt an external usb flash drive on OS10.14 mojave

I am trying to encrypt a SanDisk Connect 64GB usb drive on a macbook running OS 10.14. I followed the instruction here

https://support.apple.com/guide/disk-utility/encrypt-and-protect-a-disk-with-a-password-dskutl35612/18.0/mac/10.14

However, in step 5. I do NOT see the option of choosing between "...choose either APFS (Encrypted) or Mac OS Extended (Journaled, Encrypted)". Only options are

1) Mac OS Extended (Journaled)

2) Mac OS Extended (Case-sensitive, Journaled)

3) MS-DOS (FAT)

4) Ex-FAT

Any help would be appreciated.

Thanks

SM