Please follow the steps below;
1. Open your mac’s security and privacy settings. Open Settings -> Security and privacy setting.
2. Under the General tab, click on (Anywhere) under (Allow applications downloaded from:). See the image.
3. Download the tool from here
4. Extract the file and place the tool on your Desktop. Please do not run the tool from an USB device because it will not work.
5. To install the fonts, press the install fonts button. You will be asked for the user’s password.
6. To install the keyboard layout, press the install keyboard layout button. You will be asked for the user’s password.
7. Go to settings -> Keyboard. Press on the input sources and press the add button. A window will pop up. In the search box, type assyrian. An entry in the list will show up. Select it and press Add.
8. Now Assyrian is added.