Hi Cyprien,
If you have installed the Spike x64 application on your PC, you can get the 64-bit version of the ftd2xx.dll library from the Spike installation directory at C:/Program Files/Signal Hound/Spike/
You will see the ftd2xx.dll file that Spike uses, which you can copy into the same directory as the bb_api.dll file for your application. This should resolve the error you are seeing.
Regards,
A.J.