got me some time to figure this one out too
a wood pillar should appear (if it doesnt its a bug i guess) on the far right of the island and you "repair" it, then give anchors to three workeers and they will use them on the pillar as a task, then the bridge appears and again you "repair" it with ten wood. the mechanism is similar to the taxi, when the sign appeared in the harbor

It flashes but won’t let the cursor go near it which is annoying so can’t tell anyone to repair it! My cursor gets stuck on the lower part of the edge! I couldn’t click the taxi either so she disappeared and has never returned but I’ll give it another go tomorrow! Thank you!