Hey Nikki! Harmonics on any stringed instrument are most commonly played in the middle of the string, but also very often in the situation you are asking about. You can play a harmonic on any of the 4 strings, in the same position as you would play a 3rd or 4th finger in 1st position. So on the A string, you can play a harmonic by hovering your finger over the D and playing, as well as the E.
To get a harmonic to sound, you have to have no pressure on the string. The best word would be “hover,” as any puncture into the string will kill it. Think of a feature resting on the string—that is how little you have to press to get the harmonic sound (it should be very high pitch an octave higher). Also you have to make sure your finger is in the perfect spot or the harmonic won’t sound.
Regarding your question about the recording. If you heard the same pitch as a normal “D,” the recording is not including the harmonic. The sound will be much different when this is played. Are you 100% sure the music is showing a harmonic? It is indicated by a white dot about half the size of a half note circle.