If you are looking for the official installer, it is highly recommended to avoid third-party "Intro" files which may be untrustworthy.
: Many older Mac installers fail because their digital certificates have expired. A common workaround is to temporarily change your Mac's system date (via Terminal) to a date in 2017 before running the installer. Download File RG_Complete-Suite-2017-Mac-INTRO-...
: Locate the .pkg file inside and double-click it. If you are looking for the official installer,
: The most reliable way to download legacy Red Giant products is through the Maxon App or the Maxon Legacy Downloads page. Download File RG_Complete-Suite-2017-Mac-INTRO-...