Firstly, introducing the great man, here is Ramòn Llull’s statue in Palma, Mallorca.

This early drawing was in one of Ramòn Llull’s religious books called “Ars compendiosa inveniendi veritatem” - part of his “Ars Magna” (Great Art) series of religious writings.
As you can see it has the seven Virtues (Spes = Hope) around the outside with the seven Vices (Gula = Gluttony) in between so it is a 14-point diagram. The two sets only connect in themselves (red lines for Vices and probably green lines for Virtues) so the diagram is not a true ‘mystic rose’. This comes later in a book called “Ars brevis”
This is a 9-point mystic rose with the name of the “divine atributes” placed around the circle. They are: Veritas (Truth) Gloria (Glory) Bonitas (Goodness) Magnitudo (Greatness) Duratio (Eternity) Potestas (Power) Sapientia (Wisdom) Voluntas (Will) and Virtus (Virtue).
Lastly why a rose? Perhaps because it resembles a rose window found in many cathedrals worldwide. This is at the Basilique Cathédrale Saint-Denis in the northern part of Paris.