Mac installation problem. Shield & Internal Error

I have been trying to install Avast Free for Mac and have 2 errors right from the start.
The 1st is an Internal Error which says see system log for info and the 2nd says that I have to go to System Securty and allow extensions.

Web, Mail and Ransomware Shields are giving Error messages.

I’ve disabled Firewall in case that was an issue but that hasn’t made any difference.
I’ve opened up Privacy and Avast doesn’t show up, so I’m finding it difficult to allow access.

Anyone have a remedy please?

TIA

I can definitely help with the second error. Please follow https://support.avast.com/en-ww/article/Mac-Security-High-Sierra-allow-extensions . We wrote an article for it when this security change appeared in High Sierra. You need to click the “Allow” button in the Security&Privacy. A restart may help too.

Would you mind to send your support package to help us with the error #1 ? Help > Avast Technical Support > Generate Support Package (https://support.avast.com/en-ww/article/Submit-Mac-Security-support-file)

Thank you for your assistance.