I’d go to my boss or client and tell them I can’t get it done under the constraints and suggest an alternative stack that I’m familiar with. With a five minute conversation I can save days of heartache.
If I was young and I needed the money and experience to use as a stepping block for my career, I’d spend 12–14 hours a day trying to get it done. I either succeed and get it in under the deadline or I don’t and I have to present an unfinished application on the deadline. My boss / client will already know it’s not finished but will hopefully appreciate my good-faith effort.