Logger Pro 3.16 supports macOS 10.13 (High Sierra) and newer. Older operating systems will not open the DMG installer and may display the reason as no mountable file systems. This means your Mac operating system is not supported.
Older versions of Logger Pro are available for older operating systems.
To determine which version of Logger Pro will work with your operating system, see the table in the FAQ section headed “Do you have Logger Pro versions for older operating systems?”.