Unsigned Repository

Receiving the following error on installation in Ubuntu:

passbolt-repo-setup.ce.sh: OK

The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY DE8B853FC155581D
Reading package lists… Done
W: GPG error: download.passbolt.com/ce/ubuntu focal InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY DE8B853FC155581D
E: The repository ‘https://download.passbolt.com/ce/ubuntu focal InRelease’ is not signed.

When I traverse to that directory there is indeed nothing there. Installation aborts. I saw there were issues with sigs/keys in the past and wondering if perhaps it is rearing its ugly head again?
Thanks for any assistance.

Mark