How do I open the LO 5.0.4 Mac OS_x86-64_sdk-1.dmg download?

I have the download, and I had LO on the IMac a couple a months ago, but now it’s gone and I can’t figure out how to open the new download.

Thanks,

BTW, OSX Yosemite version 10.10.5

Try double clicking on the .dmg file.