If you already have an OAuth2 access token, you can pass it in the "Authorization" header:

wget --header "Authorization: Bearer <your access token>" -O file "https://docs.google.com/spreadsheets/d/LONG_ID_STRING/export?gid=0&format=csv"

Unfortunately, that's the simple part. Getting an OAuth2 access token on the command line is more challenging.

You should first create your own project in the API Console or Cloud Platform console, which will give you your own OAuth2 client id and client secret.

Next, from the Google OAuth2 Developer Playground at https://developers.google.com/oauthplayground/, you could then get an access token (and more importantly, a refresh token) with offline access, for the scopes https://www.googleapis.com/auth/spreadsheets (and probably https://www.googleapis.com/auth/drive), using your Client Id and Client Secret under the "OAuth 2.0 configuration" (it's the Settings icon - the little gear in the top right), by checking "Use your own OAuth credentials".

After you've added your client id and client secret, you can work through the steps on the left to ultimately get an access token and the refresh token.