NaNoWriMo Special trial - install problem

Downloaded the MacOS file and trying to install but keep getting an error

Warning: Following disk images could not be opened. reason: no child process

Any tips to fix this?

When you Get Info on the DMG file in the Finder, how big is it? It sounds like you got a partial download for one reason or another.

problem solved. friend suggested i reboot. not sure what the issue was but a re-download fixed it after the reboot