DOWNY ball (By the Mountain View Caltrain)

I don't use Downy; I use white vinegar as a rinse aid, and I am tired of having to babysit top-loader washers in our complex laundry room to pour in the vinegar at the right time. Top-loaders, unlike more modern front-loaders, don't have a dedicated compartment and have to be babysat. AI suggested that a Downy ball would let me fill it with vinegar, throw it in at the very beginning, and have it dispense automatically later, without me having to babysit the washer. That would be splendid!
The picture shows a 3-pack, but I only need 1, max 2 balls. TIA!