Element is an aggregation platform. In order to be compatible with various platform protocols, Element API uses 0x000000000000000000000000000000000000000 to represent the Native Token. However, in the operation of contract interaction and signature, it is necessary to follow the original Native Token definition of each platform. Where Element is 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeeEEeE, OpenSea、LooksRare is 0x000000000000000000000000000000000000000.
You must use the 'v1/orders/fetchExchangeData' API to fetch exchangeData of this order, then use 'exchangeData.erc20Token' to interact with contracts.