R900 voucher for 87th anniversary

I received an message via Whatsapp that Woolworth is giving away R900 vouchers for their 87th anniversary. I followed all the instructions and send it to 20 people on WhatsApp. Then when I wanted to claim my voucher I can’t pass the second step. It doesn’t allow me to click yes on the tab that says “yes” that I’m over 18 years. Be careful as I think this is not real.