After downloading the Mac OSX SimUText installer file, the DMG fails to mount, or you see a second DMG file including the word, "Part"
The installer DMG file did not fully download, the download was interrupted, or otherwise damaged.
Download again and wait for the download to complete before opening the DMG file.
If the problem persists, the network connection may not be reliable enough for a large download. You can download the DMG file on another computer and copy it to the computer you want to install it on.
Or if you are using a laptop, connect to a more reliable network and try again.