Every new MG gets a Welcome Package (swag) when they register for the first time at Arcadia Spire. Some get more than others; Mai got the “extended package”, which has more stuff than the basic package. This happened in ch.36.
Items all MGs get:
Association-issued communicators: “They are advanced pieces of magitech, and fit into your ears like Bluetooth earbuds. These have a variety of useful functions beyond just allowing you to communicate with support personnel. … if they are damaged or lost, you'll have to pay for replacements.” Edward ch. 36.
Information on joining the Guardian Academy.
A bank account with an associated debit card.
Items that Mai got that not all MGs get:
A card that gives a 100-point discount on a purchase from a crafting-focused Magical Girl.
A book containing a list of support Guardians and the services they offer. (Note: I don't know why everyone doesn't get this one, and wonder if Mika just forgot to list it.)
A "small card informing me that I would be gaining priority access to "AS:D" at the Guardian Academy (something Selene assured would be explained best at the academy, and that it would be incredibly useful)."
A waiver to claim any basic Astral Shift enchantment for free.
A voucher giving her one free meal a day from the tavern on the 10th floor of the Arcadia Spire.