If a message like this appear:
Worry not.
Just right click (or ctrl+click) over AudioStellar icon inside Applications folder and then click Open.
Next, try opening the application. A similar message will appear but now we have the Open button.
If a message like this appear:
Worry not.
Go to your settings panel, and click on "Security & privacy"
On the general tab, click on "Open Anyway"
Next, try opening the application. A similar message will appear but now we have the Open button.
Find more info at: https://support.apple.com/en-us/HT202491