Disney has a per-package handling fee of $5 for packages you send to the resort. You can send a package to your resort's specific address and address it to the lead name on the reservation, e.g. "John Smith, Guest, arrival: [provide date]." (Disney wants the package to say it is for a guest and the arrival date.) You pick the package up at the business centers for those resorts attached to a Disney resort that has them (BWV, VGF, BCV and BLT), otherwise at the front desk or concierge desk. As with any package delivery service, there is always some small risk of something being lost or damaged, but that is seldom an issue.
For discussion of delivery to a resort and applicable addresses, see
https://www.disboards.com/threads/shipping-to-and-from-disney-resorts-faq-new.3435904/ but note that thread was started when the $5 fee was applicable only to resorts with business centers and in April 2017, it was changed to apply to all resorts. As you will notice in the last several pages of the thread, the fee has not always been charged at Disney resorts without business centers even though the rule changed in April 2017, and thus apparently the hotels may have some discretion as to whether it is charged.