Create an account just for the card and log each purchase made with it. To pay the card, make a transfer from the account the money comes from, or use a balance correction.
Card statement
In All spending, filter by the card's account and choose a cycle that matches your statement to see each period's spending.
Payment reminder
Create a repeating transfer, or an upcoming transaction, for the payment day: Macuta reminds you as the date gets close. If the amount changes every month, use an upcoming transaction (not a transfer) with amount 0 and turn off Auto pay transactions: when you mark it as paid, Macuta asks for the amount. See Future transactions.
Card budget
Create a budget with the limit you want and choose the card's account. Start it on your statement date so the totals match the statement.