After you have done this, disable any antivirus, firewall, VPN, or proxy software that might be active on your computer. These tools are sometimes known to interfere with the installer’s ability to download the model files.
Please also ensure that the Topaz Photo AI installer has all the proper settings in your system by going to your Mac System Settings > Privacy & Security tab and scrolling down to the security section. You will want to make sure you have 'App Store and identified developers ’ selected. Here is a video example: