If your computer currently has an existing system-wide network proxy set up (e.g. for accessing restricted online content), you will need to enter the associated credentials when you first start ReadCube. The message box will ask "Please enter your internet network proxy credentials". You should input the same username and password that were used to set up the system network proxy. ReadCube will save these credentials so you will not have to re-enter them again.
Please note, this is not the same thing as an institutional/library EZProxy, which can be set up via a different process. Generally, if you access articles via a network proxy instead of a library proxy, you should set ReadCube's Institutional Affiliation to "none" in the app preferences.
If you encounter this network proxy message and do not know what credentials to enter, please contact your IT administrator.
For any other questions, please contact us at support@readcube.com.