You will need to deploy a smart contract. You can do so by following this tutorial:
https://github.com/XRPL-Commons/xrpl-commons-january-2024/tree/main/apps/lending-contract
Once you have a smart contract address on the EVM sidechain, you can update the contractAddress variable in script.js
with this information.
If you have node you can use serve:
https://www.npmjs.com/package/serve
npm install --global serve
then navigate to the root of this project
serve