I have some information about matching bulk transactions. Matching transactions means you'll need to make sure that there are no duplicate records in your QBO. Thus, matching them in bulk isn't possible. You'll have to link each transaction one at a time. Though, you can add bulk transactions at once.
To add in bulk:
Go to the Banking menu, then select Banking.
Highlight the bank account you want to link your downloaded transactions.
Tick the box next to Date or the box next to the transactions you wish to bulk add.