Step 1

Create a bitly account to get started bitly's account. Sign in and go to Step 2 if you already have a bitly account.

Your account should look like the below image :

Step 2

On the top-right corner click on "Settings" and navigate to Options > Settings > Advanced Settings

Step 3

Click on the link "OAuth" in Advanced Settings.

Step 4

Now you can see your Generic Access Token.

Note : If you have just created a new account on bitly then you will have to verify your email first and then you can generate access token otherwise you can just enter bitly account password and generate access token.