You have to have the service added to your Lyft account in order to use it.
It is only automatic for those staying at Deluxe and Villa resorts.
Those staying at other resorts can ask Bell Services at one of the Deluxe or Villa resorts to add it to their Lyft account. Results are mixed, some have had success with this, some have not. It can not hurt to ask, if you have a chance of getting by one sometime before your reservation. I would try Poly first, explain that you have a reservation at Ohana and would like to use Minnie Van, if you have children that need car seats I would tell them that too. I am not sure what circumstances allow them to offer it to non-Resort guests. May just be as simple as they can add so many per day or even just how that individual feels. Honestly just guessing.