QuickBooks Online automatically downloads transactions every night when you connect a bank account to online banking, kirchoff.
Usually, it takes 2-3 business days for banks to relay transactions to QuickBooks, However, the data will depend on what your bank shares with us.
If it's still not reflecting, I recommend refreshing the connection to get the latest available transactions. You can click the Update button in QuickBooks Banking to check if your latest transactions will reflect.