It is most likely that your company is implementing HTTP filtering rules using something like a Web Application Firewall or Web Proxy and that the outbound connections from your app to the JourneyApps infrastructure are being blocked.
You will need to work with your IT Infrastructure team to ensure that all the hostnames used by the JourneyApps application are whitelisted and allowed. The full list of hostnames are here:
The following guide details which hostnames should be whitelisted (egress connections on TCP 443 i.e. HTTPS):