Hi,
Would someone please tell me what hardware I need to attach the boom to the mast?
Thank you!

The Sunfish uses a gooseneck (sort of)
https://www.sunfishsailbo…ck_Assembly_p/90638.htm=
I guess you should pull it down with a downhaul line.

Or just tie the boom to the mast with a couple clove hitches, we did so several decades ago. The mast came with no shrouds, a good line is enough. Forestay is not needed