Here is Arduino integration section as below URL.
There is integration guide.
There is no intergration guide on there any more
the old guide said this but this call is not in the libary.
/* Call to the function which initializes the BSEC library
* Switch on ultra-low-power mode and subtract a 5 degrees temperature offset */
ret = bsec_iot_init(BSEC_SAMPLE_RATE_ULP, 5.0f, bus_write, bus_read, sleep, state_load,
You can download bsec library in this url as well.
I checekd that there is integration guide.