Does anyone know if we need reservations if we purchased from Groupon?

No but you have to wait 72 hours after purchase to use it

You just have to wait a day before you use it. For example, if you buy it on Tuesday anytime before 12 A.M. and you can use it Wednesday

You can use it the next day

I dont believe you do unless your groupon says it. I know most groupon u cant use same day as u buy it.