Lights say 4.5V 0.15A, and there are 14 bulbs. 4.5*0.15*14 = 9.45W, and at 6v, that's 1.58A. If you assume the circuit's about 50% efficient, you need about a 6VAC, 3A power supply. It looks as if the first thing the power goes to is the slide switch, and then D1-D4 are a full-wave diode rectifier, followed by the big capacitor next to D1-D4, so you could feed this with either AC or DC power, of either polarity. HCF4017 is a hex flip-flop, probably connected to make the lights twinkle.

6V AC or DC, either polarity, about 3A. I'd try https://smile.amazon.com/6V-Power-Supply-COOLM-Transformer/dp/B08BCBZ632/, assuming the connector fits.