Attempting to install on Mac OS 10.10.5
Downloaded dmg file from: https://sourceforge.net/projects/exiftool/files/
You can see in the attachment that when I doubled clicked on the dmg file, I got a new folder.
I doubled clicked on the pkg file, but pkg didn't load as expected. I got my catchall file expander.
So There could be something wrong with my mac or the pkg file isn't made correctly. I included three screen captures as attachments
mac $ ls -lR /Volumes/ExifTool-10.36/ExifTool-10.36.pkg
total 0
drwxr-xr-x 7 mac staff 238B Nov 24 09:39 Contents/
/Volumes/ExifTool-10.36/ExifTool-10.36.pkg/Contents:
total 5288
-rw-r--r-- 1 mac staff 45K Nov 24 09:39 Archive.bom
-rw-r--r-- 1 mac staff 2.5M Nov 24 09:39 Archive.pax.gz
-rw-r--r-- 1 mac staff 1.2K Nov 24 09:39 Info.plist
-rw-r--r--@ 1 mac staff 8B Nov 24 09:39 PkgInfo
drwxr-xr-x 7 mac staff 238B Nov 24 09:39 Resources/
/Volumes/ExifTool-10.36/ExifTool-10.36.pkg/Contents/Resources:
total 16
drwxr-xr-x 5 mac staff 170B Nov 24 09:39 CVS/
drwxr-xr-x 6 mac staff 204B Nov 24 09:39 en.lproj/
-rw-r--r--@ 1 mac staff 19B Nov 24 09:39 package_version
-rwxr-xr-x@ 1 mac staff 494B Jul 23 2015 preflight*
/Volumes/ExifTool-10.36/ExifTool-10.36.pkg/Contents/Resources/CVS:
total 24
-rwxr-xr-x 1 mac staff 44B Jul 23 2015 Entries*
-rwxr-xr-x 1 mac staff 16B Jul 9 2015 Repository*
-rwxr-xr-x 1 mac staff 49B Jul 9 2015 Root*
/Volumes/ExifTool-10.36/ExifTool-10.36.pkg/Contents/Resources/en.lproj:
total 152
-rw-r--r-- 1 mac staff 308B Nov 24 09:39 Description.plist
-rw-r--r-- 1 mac staff 635B Jan 28 2007 ReadMe
-rw-r--r-- 1 mac staff 406B Jan 28 2007 Welcome
-rw-r--r-- 1 mac staff 60K Jan 28 2007 background
mac $
I think you missed one important system message when you double clicked the pkg inside the dmg. Depending on your OS version and settings you should have gotten a message stating that the application was from an unidentified developer, rejecting install. This is normal.
To install the package anyway, right click the pkg and choose open. You'll then need to provide your admin password as confirmation you really want to run the program and after you have done so, the installer will start as usual. Note that this is the standard macOS Gatekeeper procedure for this type of install (from e.g. small developers).
Hope this helps.
P.S. Instead of downloading from sourceforge you could also have downloaded directly from the "source (http://www.exiftool.org/ExifTool-10.36.dmg)".
It is a problem with my system. I installed the "I Spy.app". It was grabbing the .pkg files types as its own. Manually, picked the opening app as install.app and exiftool installed.
Robert