Simonas, the most common cause for that type of error is that IntelliJ IDEA isn't configured properly for a required network proxy server. Please make sure that the settings under
Appearance & Behavior>System Settings>HTTP Proxy are correct, and note that the licensing software cannot use auto-detect proxy settings so manual proxy configuration will be required. If that doesn't resolve the issue for you, let me know either here or via
sup...@illuminatedcloud.com and I'll help you get the license activated.
Best regards,
Scott Wells