Because of the RMRK Multi-Asset feature, which allows a single NFT to have multiple outputs, we need to add Asset entry to the Collection before we can let the NFT have output.

Asset ID: The unique ID of Asset under current Collection

Metadata: Asset Metadata URI

Is Catalog Related Asset: If this parameter is checked, you can add CatalogRelatedAssets. For details, see Create Catalog, add CatalogRelatedAsset and full equipment process implementation

After adding the Asset entry, you can add the Asset to the NFT, see Add Asset to Token