GY-BMI160 module conferting raw data to degrees

Good morning,

I want to use a gyroscope as an encoder to calculate the angle of my robot arm head. My robot arm used 4 stepper motors to move his x,y,z,a axis and a servo for his claw. The a axis is for angering the claw that needs to face downwards no matter the position the robot arm (Kind of like a claw arcade game)

As gyroscope i use a GY-BMI160 module.

and i use the Hanyazou's libary for the module. (GitHub - hanyazou/BMI160-Arduino)

There i use the SPI mode to get data from the gyroscope but, the data that i am getting is "RAW" data. This "RAW" data is about all over the place while moving the module. I have looked though some forum post where i found that the data is "RAW" and needs to be converted but, can't find anywhere how to convert the "RAW" data into degrees.

I did found tutorials on how to do it with the MPU6050 but, i don't have one.