The Mac's built-in security will detect that the app has been downloaded from the internet, and will therefore be suspicious.
However, the app is safe and virus-free - at time of writing.
If you are happy to circumvent the warnings, it is recommended you do the following:
1. Go to System Preferences (
menu)
2. Go to Security & Privacy | General tab
3. Under the section Allow apps downloaded from:
it should state that "StitchThis.pkg" was blocked from use because it is not from an identified developer.
Alongside this message, there should be a button labelled Open Anyway.
Click on this, and it should then pop up a message saying
"MacOS cannot verify the developer of "StitchThis.pkg". Are you sure you want to open it?
There will be a button that says Open below this.
Click on that, and the installation package should open normally.
On the latest version of macOS: if you try to double-click the package, you get a dialog with the following:
"StitchThis.pkg" Not Opened
Click on Done, NOT Move to Bin
In System Preferences ( menu), go to Privacy & Security | Security subheading
"StitchThis.pkg" was blocked to protect your Mac: click Open Anyway
Dialog appears, asking you if it should Open "StitchThis.pkg"?
Click Open Anyway, NOT Move to Bin
It will present you with a further dialog, labelled Privacy & Security...
Enter an administrator's username and password to allow this.
Do so, and click OK.
