You can buy a motorcycle and then trailer it away from the dealer or lot without having a motorcycle insurance policy or a motorcycle license.
However if you plan to drive the motorcycle off the lot then you'll need to have a motorcycle license as well as show proof of motorcycle insurance before the dealer will allow you to drive the motorcycle off the lot even after you pay for it.
Also when you go to register your motorcycle you'll need to have motorcycle insurance as well as your motorcycle license to get the motorcycle registered.
So it's best to get the motorcycle insurance coverage when you plan to buy the motorcycle however you'll need the information from the motorcycle to get the insurance but you can buy the motorcycle and then go to the insurance company and buy motorcycle insurance.
And then show proof of the motorcycle insurance to the motorcycle dealership and then you can drive off the lot with the motorcycle.
But you can just trailer the motorcycle without a motorcycle license or motorcycle insurance and then get it later when you plan to ride the motorcycle.