The software updater gives me error as below while checking for updates
Failed to download repository information
I am using Zorin OS 15.3 lite version and while I run the command
sudo apt-get update
I get the following response
Hit:1 Index of /ubuntu/ bionic InRelease
Hit:2 Index of /ubuntu/ bionic-updates InRelease
Hit:3 Index of /ubuntu/ bionic-backports InRelease
Hit:4 Index of /zorinos/apps/ubuntu bionic InRelease
Get:5 Index of /repos/edge/ stable InRelease [7,343 B]
Hit:6 Index of /zorinos/drivers/ubuntu bionic InRelease
Hit:7 https://debrepo.freedownloadmanager.org bionic InRelease
Hit:8 Index of /zorinos/patches/ubuntu bionic InRelease
Hit:9 Index of /stable/ bionic InRelease
Hit:10 Index of /patches/ bionic InRelease
Hit:11 Index of /zorinos/stable/ubuntu bionic InRelease
Err:5 Index of /repos/edge/ stable InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EB3E94ADBE1229CF
Hit:12 Index of /apps/ bionic InRelease
Hit:13 Index of /drivers/ bionic InRelease
Hit:14 Index of /ubuntu bionic-security InRelease
Reading package lists... Done
W: GPG error: Index of /repos/edge/ stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY EB3E94ADBE1229CF
E: The repository 'Index of /repos/edge/ stable InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
Any ideas where I should look ?