ESTA stands for Electronic System for Travel Authorization. Travellers from the Netherlands, most of the EU, the UK and a few dozen other countries fill it in online, pay a small fee and can enter the United States for up to 90 days without a visa.
What it allows
Tourism, meetings, showcases where nobody is paid, and a conference. An artist flying to a festival for a paid set is working, and ESTA does not allow work. Playing anyway and getting caught means refusal at the border, a cancelled show and trouble on every later trip.
What an artist needs instead
A work visa: the O-1 visa for an artist with a record of recognition, or the P-1 visa for a touring artist or group. Both take months, need a petition filed in the United States and cost real money, so the agent starts the paperwork the moment a US date is confirmed.
The one exception
A showcase, competition or festival with no fee and no expenses paid beyond travel may fall under the visitor rules. Check the current guidance before relying on it, and keep the invitation letter to hand.