Basically, Sentry AI works well with all basic default setting of Blue Iris.

When Blue Iris detects motion, the first frame in the clip, i.e. the image seen in the clip list (below) is sent to Sentry AI via the internet for processing. Sentry AI determines if human activity is associated with the frame and marks the clip in clip list as seen below.

Blue Iris motion detection is the start of the trigger pipeline.  Sentry AI will only work if Blue Iris motion detection is activated first.