Given that all URLs of the journal are under a login protection, I believe this must be blocking the process, as the server will attempt to access some URLs on your end (e.g. https://epistemehealth.com/index.php/nab/gateway/plugin/PLNGatewayPlugin)
I’ll check with someone if it’s required to have a public journal in order to join the PKP PN, I didn’t see this information in the agreement nor the requirements… If not, I’ll create an issue to handle this situation.
So for now, you can disable the login protection (at least to check if it works), or wait me to confirm if it’s a bug and provide a fix.
Best,
Jonas