What are the required things to retrieve the data from google analytics using client id and client secret
<p>I can generated the client id and client secret from the google developer window.
Also i created c# program to fetch the data from google analytics api with generated client id and client secret.</p>

<p>Through c# program i can fetch the data successfully.
But for first time it asks me to login with my gmail account like below image and I clicked allow. 
<a href="http://i.stack.imgur.com/wCGkt.png" rel="nofollow">Gmail login page.</a>
<a href="http://i.stack.imgur.com/SpCM4.png" rel="nofollow">Allow deny page to access gmail data.</a></p>

<p>After clicking allow I can retrieve the data.
I tried to use same c# application in another system.
There i have to login for another time and clicked allow for the given gmail account.
My question</p>

<p>Is Gmail username and password is necessary to retrieve the data from the google analytics using client id and client secret ?
The above login and allow pages appear only for first time, then it retrieves the data.</p>

<p>Also I tried with service account.
There I  used only json file to retrive the data.
There I cannot get login and allow page to retrieve the data.</p>