Dear RushFiles Users,
Some of our users reported that they receive a message saying "Installer.pkg can't be opened because Apple cannot check it for malicious software." There's only an OK button with this message, and the client seemingly can't be installed.
If you encounter this, please go to System Preferences -> Security & Privacy -> General. Here, make sure that "Allow apps downloaded from" is set to "App Store and identified developers". You might need to click the little lock icon and type in your Mac's password to make changes on this page.
After you've set this setting, you will be able to install the client.