Hi @timothy_chen,
Welcome to the community 
What version of truffle are you using?
Can you share the dapp sample code GitHub repository?
There was previously issues with Node version 12, where either downgrading node or using specific tool versions were required. (Node 12 issue with Truffle)
OpenZeppelin Starter Kits are a great place to start with dapp development, see the documentation for details: https://docs.openzeppelin.com/starter-kits/2.3/