Invalid OAuth token error

[BarryCarlyon]

@rouq1567

By the way, how can I use the API using the token I received now?

You have already posted the answer:

@rouq1567

axios.create({
baseURL: 'https://api.twitch.tv/helix',
timeout: 6000,
headers:{
    'Client-ID':'id',
    'Authorization':'Bearer <access token>'
}

Step 3 you exchange the ?code for a token.
Then you take the token from the JSON blob and use that in API requests