Which model of Brake Buddy do you have? We had an older "Classic" and it had to be activated "manually" (meaning push a button those 5 times) to bleed the toad's vacuum. I don't remember what happened next.
We now have "Vantage Select" and it pumps up automatically when plugged in. More later about Plugged In... Then there's "start" or some button to that effect. Pressing causes "Vantage Select" to do the five activations. After that, a green light should come on "normal."
Brake Buddy's support line is excellent as noted above. They can help with its operation, and if you don't have this, ask for a direct-to-battery power socket. Many modern vehicles' "power outlet" does not supply the solid 15-amps needed for a BB to operate properly.