The quota of 300,000 yuan is basically the platinum card in the series of diamonds and platinum cards of CCB. If it is this kind of card, the card itself has an annual fee. The annual fee standard of Platinum Credit Card (Elite Edition and Premium Edition) is 1.800 yuan/card (supplementary card 1.200 yuan/card). Because the card is charged an annual fee, there is no requirement for the number of swipes.
The standard platinum card of CCB is free of annual fee 10, but the amount of this card seems to be less than 300,000. If it is really 300,000, it is likely to be a temporary quota.
So please ask the landlord after confirming the card type.