I used the file from the development machine (it’s easier to bring this to direct internet access then the server behind the proxy).
I copied the file C:\ProgramData\IceTeaGroup\Wisej\wisej-developer.lic to the same path on the server and renamed it as wisej-server.lic
The error message has been replaced by a trial information message.
It probably means that the proxy is blocking the http request. You can activate from a server (or development machine) that has access to the internet and allows http requests to wisej.com and then copy wisej-server.lic with your project. The file is created in the same project folder.