Where do I enter 1042-S information to reclaim the tax withholding?

This TurboTax FAQ tells you where you can report foreign income, pension, and other foreign amounts:

https://turbotax.community.intuit.ca/community/other-income/help/how-do-i-report-foreign-income-foreign-pension-and-other-foreign-amounts/00/873599

You can then apply for the Foreign Tax Credit if applicable.