Connecting the enable pin to 5V will enable the beacon for both transmission and reception. Please note that the GPIO pins of the Raspberry Pi are not 5V tolerant, so you will need to use something like our bidirectional logic level shifter to interface the Raspberry Pi with 5V systems like the output and enable pins on the IR beacons:
If you want to be able to turn the beacon on and off with your program, you could connect the enable pin of the beacon to a GPIO pin on the Raspberry Pi.
The + and - pins are the power connections for the beacons. You should not try to power the beacons from your Raspberry Pi. You can power them from a separate power source, or if you are already using a battery pack in your system that is between 6V and 16V, you could connect those power connections to the battery directly. Please note that if you use a separate battery pack, you will need a common ground between the Raspberry Pi and your IR beacon.
9V batteries like those cannot supply very much current. I suggest trying rechargable battery pack with AA cells, or a LiPo battery pack, and seeing if that helps. Also, I do not see any GND connection between the IR beacon and the Raspberry Pi, so you probably do not have a complete circuit for enabling the IR beacon. Can you try connecting a common GND between the regulator and the Raspberry Pi?