Won't install because other app is blocking it - even though that app is completely uninstalled

I've tried multiple times to download AVG. However, I keep getting an error message that Avast is installed, therefore blocking AVG. I've uninstalled Avast in every which way possible, but I still get the error message. 

Please please please help!!

I can't share a screenshot. The ability to do so is somehow disabled. I do see the option to attach an image, but my screen freezes when the prompt to choose a picture comes up. You can copy and paste that video URL into your browser. Otherwise, is there an email address where I can send a screenshot?

Yes, Jessica.
I have sent an email to you. You can attach the screenshot in a reply to that email.

Hello Jessica,

We'll certainly look into this & help you.
Initially, please share us the screenshot of the error message you've been receiving, so that we can check & assist you further.
You can post the screenshot here in your topic. Click on Answer & then click on the Image [mountain symbol] & follow the instructions.
Also, kindly specify the operating system of your computer.
Awaiting your response.

Midhun,

Thank you for your prompt response. I am running the latest Catalina OS on my 2017 Macbook Air. Here is a video of my screen (taken with the Loom application). Won't install because other app is blocking it - even tho... | AVG | Loom

We are unable to access the provided link, Jessica
Kindly share us the screenshots of it, so that we can check and assist you further.

Hello Jessica,

We'll certainly look into this & help you.
Initially, please share us the screenshot of the error message you've been receiving, so that we can check & assist you further.
You can post the screenshot here in your topic. Click on Answer & then click on the Image [mountain symbol] & follow the instructions.
Also, kindly specify the operating system of your computer.
Awaiting your response.

We are unable to access the provided link, Jessica
Kindly share us the screenshots of it, so that we can check and assist you further.