Control relay from sensor output when LOW is 0.2V
There is a basic digital wiring diagram in page 11 of the datasheet you have linked



There is a note (and the specs table has this too) that the sensor can only source 100uA, so you need to use a high value resistor for the base, something like 100k which will sink about 43uA (assuming 5v supply) and a resistor from base to ground in the range of 1000K or so.
As a load in the collector you should place a resistor of about 10K-100K (I would say 47k).

This will still not solve the hysteresis problem, the transistor will turn on/off rapidly when the sensor detects motion.

One solution for that is to feed a pin of your mcu from the collector of the transistor, detect the change and apply the delay in software.

The other solution is the circuit provided in the same page of the datasheet that uses a timer to add delay