If you want to know how to get lucky boxes, here's a more general answer. (This could be a long read)
The way Lucky Box works is the same way how roulettes worked in T6. In TTT2, there are four ways to get lucky box, one is the definite lucky box which comes in at a certain point in your record, two is from additional lucky box opportunities found in lucky boxes, three is from other players with lucky box and four is from Ghost Battle in offline mode.
To get the definite lucky boxes, you just keep track of your player record (win-loss).Your first lucky box should be at exactly game 10. Each additional lucky box will occur 40 games after initial. So for example, if your w-l ratio is 6-3 (5+4 = 9), then your next game should have a lucky box. Your next lucky box should be at game 50, 90, 130 and so on. This way you'll know you are surely guaranteed a lucky box.
It is also possible to get additional lucky boxes from an initial lucky box. There are four lucky box colors, there's silver, blue, red and gold. Silver is standard lucky box that just gives you money, about 50,000g. Blue is an upgraded version of silver that gives a lot more money, 200,000g-500,000g. Red is special box, it will either give you rage, item or sometimes even more lucky boxes. Gold is special to ghost battle. it only gives items (if by chance that character has nothing more to unlock, you get 765,000g). To get gold boxes, you have to choose the ghosts that have gold trimming on the ghost selection after every match in ghost battle.
Lucky boxes can also be shared with other players, if you play online, you share that lucky box with your opponent. If both your accounts have lucky box, they occur concurrently (meaning both of you use up your lucky box when you play each other).
Also note, in the event a lucky box is achieved and an item is won, the character/team you are using is the one who will get the item. For example, let's say you are using Yoshi/Kuni team against Paul/Law team and items are unlocked. If you check your customizations, Yoshi and Kuni will have unlocked a new item but not Paul/Law. It goes the same way for the opponent if you're playing online, they unlock for their team but not your team.
And another note about gold boxes in Ghost Battle. Items are unlocked for the "point ghost character", not the team you are using. Let's say you are using Yoshi/Kuni team and choose a Jun/Asuka team as next match. When you get the gold lucky box, only Jun gets the box because she is on point. Neither Yoshi, Kuni nor Asuka get anything. So pick your ghosts well.
Hope that helps.