I actually think Luke retrieved it and it was located at the new Jedi academy (thus Kylo also encountered it), Maz had some sort of contact or involvement with the Jedi academy, and took it after the academy massacre
Btw along with SW minute have you seen these other quality quickly rising Star Wars channels?
Antoine Bandele
The Stupendous Wave
Fact Free
SithReign
Dash Star
Lore Guy
TheCancrizans
The Mos Eisley Cantina (The Star Wars Channel)
CivilizationEx
Lunair
SciFi Soup