No, the shares do not need to be unpledged to receive REs. The REs will be credited to your demat account even if the shares are pledged.
What is book closure date?
What is buy-back of shares and will I be eligible for it?
Will I qualify for the benefits of corporate actions in stocks that have been pledged with Kotak Neo?
Will I be eligible for the benefits of corporate actions if I have pledged my stocks?