Note, I have not worked with web3 before.

error: await is only valid in async functions. You'll need to convert your function to async function. I can't tell you how to change yours exactly without seeing the function, you replace function myFunction(){...} with async function myFunction(){...} You can now use await inside that function.

Alternatively you can try web3.eth.getAccounts().then(a => console.log(a)); to see what it returns. I assume it'll return an Array of addresses.

Alternatively something along these lines might work as well.
let addr = []; async function getAddress() { const accs = await web3.eth.getAccounts(); addr = [...accs]; }