My client is unable to open the packaged App (You do not have permission)

Hello, I’m at a loss. I’ve searched around for a solution and haven’t been able to turn anything up. I apologize in advance if this post is missing key info, I am still new to all of this and am not very tech savvy.

I am doing some UE4 prototyping for a client. After many hours of work, I finally packaged the prototype for mac and sent it to the client, but no matter what we do, the client cannot open the app on his mac.

Client gets the notice “You do not have permission to open the application” (and yes, he is the admin.)

We’ve tried:

It works perfectly fine on my Mac, I am running High Sierra.

Currently waiting for a full list of specs for the client’s mac, but it’s apparently brand new. I’m wondering if there is some sort of setting I need to click when packaging? Is anyone familiar with this problem?

Client literally just needs to be able to run the app off desktop for presentation purposes.

Offering a $100 reward via Paypal to the person who posts a successful solution to this problem.

You probably figured it out by now, but you need to sign and notarize the app.
Check this guide out here: Codesign and notarize Unreal Engine Mac builds for distribution outside of the Mac store | by Parth Naik | Medium

If you have questions, let me know!