That's definitely your problem. I just checked the
MDE developer notes, and it requires 5.0 or higher. You might check with your wireless carrier. LG is actually not terrible at providing OS updates, depending on the carrier. For example, the LG G3 shipped with KitKat 4.4 back when it was released in 2014, but has since been updated to Marshmallow (6.0.1) on AT&T, T-Mobile, and Verizon.