The CyAPI.lib is compiled with Visual Studios. We have not tested using CyAPI.lib in QT applications.
To use the CyAPI with MinGW, the CyAPI source needs to be recompiled with MinGW and then statically linked in the project.
Please download the CYUSB suite from this link https://www.cypress.com/documentation/software-and-drivers/ez-usb-fx3-software-development-kit and recompile with MinGW compiler.
Please let me know if any queries on it.
Thank you for your reply, I have solved this problem a few days ago. Thank you again for your concern!