Little Snitch v5.3.2 - "Installation Failed - Failed to load network extension"

[Andy991]

Hi all,

Got the latest M1 MacOS and tried to install Little Snitch v5.3.2 and I get this error

ERROR:
Installing Little Snitch
Installation Failed
Failed to load network extension. The extensions' code signature is invalid

Downloaded the install straight from the website. As I am new to MacOS M1, any help would be appreciated.

If this isn't a good Firewall and there is a better one also let me know

Thanks