Model Loading
You need to request some models per natives, before using them. Because natives are non-blocking methods and the game wouldn't wait until the model has been loaded from disk, you need to call them as a async method. Here you can find an example, written in JavaScript how to load them correctly.
Note
If you need to load model for ped, vehicle or object consider using LocalVehicle, LocalPed or LocalObject API, these classes load the model under the hood for you.
Example
Usage of RequestModel Method
const modelHash = alt.hash('mp_m_freemode_01');
await alt.Utils.requestModel(modelHash);
natives.createPed(2, modelHash, 0, 0, 70, 0, false, false);