Hi,
From the path provided as comment above, it seem like the path is not correct as compare with https://docs.openvinotoolkit.org/latest/_docs_install_guides_VisionAcceleratorFPGA_Configure_2019R3.html in step 11.
I would like to suggest to do a clear uninstall for the BSP of both device and OpenVINO toolkit.
Then do a install of OpenVINO toolkit for Mustang-F100-A10 based on the link below:
https://docs.openvinotoolkit.org/latest/_docs_install_guides_VisionAcceleratorFPGA_Configure_2019R3.html
After you have successful run and compile sample application for Mustang-F100-A10 device, then only installed another a10_ref BSP in the same path: /opt/altera/aocl-pro-rte/aclrte-linux64/board
Thanks