You do not have to have the media system/sat nav updated, many choose to ignore it and use Android Auto/Apple Carplay for maps and entertainment, using their mobile phone connected via a USB data cable. However if like me, you are happy to use the fitted system you can get it updated by a Kia dealership, it should cost £40 and has to be requested.
Updates are released yearly, usually between April and June, however last years pandemic delayed the release until September. As a consequence there is a good chance your car still has the 2019 maps, the dealer does not have to update media system before selling the car.
Personally I would wait until the next update is released. If you look in the
Kia Customer Services section you will see when they announce updates. Last years announcement is
here.
Why they have given you a data card case I have no idea. I don't know the layout on the Stonic, but the SD Card is usually hidden under a flap which is just under the screen. You should never have a need to remove it.