It appears the BMP3-Sensor-API v2.0.1 readme.md page is incomplete , refering twice to "below code example" but there is no example implementation.
I am hoping to use the BMP390L with the Particle Argon platform. I can detect it's on the I2C bus but I need an updated example for the 2.0.1 API available on Github.
BMP3-Sensor-API v2.0.1 is latest verison.
If you want example code, one option is use BMP280 examples as reference.
Another option is, download coines, use C:\COINES\v2.2\examples\c\bmp3\read_sensor_data as reference.