To recognize your guide, look for a tall Dutchman holding a white umbrella next to the statue of Coster at de Groote Markt. The statue is located in the center of the market square and is a well-known landmark in Haarlem. The guide will typically be waiting near the statue before the tour starts, and you can approach them and introduce yourself to join the tour.
If you’re unsure whether you’re in the right place, you can also ask around and see if anyone can direct you to the meeting point. It’s a good idea to arrive a few minutes early to ensure that you don’t miss the start of the tour and to keep an eye out for the guide with the white umbrella to make sure that you’re in the right place.