The quintremolo is played with the thumb followed by 5 notes.
This tremolo is rarely used. In fact I never heard it before, and never saw it in written music. An interesting use of quintremolo combined with the classical tremolo gives a possibility to create rhythms.
Like the other tremolo's, when you play it fast every quintremolo is one beat.
A simple example is the following Andalusian cadence, based on a flamenco style called Soleares.