When you go this Google Console Link

Now check I agree (please dont ask me why.If you are patient read entired terms of service) and click on Agree and continue.That will open a page like below

Click on create Project. That will open a dialouge like this. click on create and change name if you want

Creating project will take you to dashboad which contains beolw. Now click on API & Services and select Credentials

Tha will take you to following.

Select OAuth client ID which will take you to following

Select create and Fill the required information of below

At the bottom you will have Save and continue that will take you to scopes page and there also click save and continue until you go to summary there you click on go to dashboard

Then in dashboard click on OAuth client ID which will ask you to select Appication type according to your need

That will pop open a board

You can click Download json and it will download the file

You can also create an API from create credentials and clicking on API key but you inorder to use specific API's you have to enable them from Library on side bar which will open

and search for for example "Google Sheets API" which will get

click on API and click Enable which will enable that particular API