The plug-in wants to verify its activation validity. It therefore needs to connect to our license servers. 

Please make sure that you are online. 

Although not a generally a problem, it might be better to try launching the SRDx plug-in not from within a VPN, and/or not using a proxy config, but rather a “direct” internet connection, if possible. 

SRDx communicates via the (macOS:) Photoshop app / (Windows:) Photoshop.exe, so you want this program to be able to communicate through your OS’s firewall.