If you had unopened crates in your inventory on the day of the update, they were automatically converted into "unrevealed" blueprints.
Each key was a gamble. You might get a rare decal or the ultra-rare Titanium White Zombas . The Great Conversion (December 2019) buy crates rocket league xbox one
A rotating store where you can use credits to buy specific items directly. If you had unopened crates in your inventory
Occasionally earned after matches. You pay credits to "craft" the item shown on the blueprint. buy crates rocket league xbox one
To open them, you had to purchase Keys from the Xbox Store.