Bitly API

Step 1: Go to the below URL and create a new account or if an account exists then login.

https://bitly.com/

Step 2: Once Login, Click on Settings Icon/Menu.

Step 3: After you need to Go to Account settings -> Groups. Then click on the Group Name.

Step 4: Here you can find the Group name and Domain. Copy it and paste it into your Magento 2 Bitly settings configuration.

Step 5: Now go to Developer settings -> API to generate Bitly token. Enter the current login user password and click on the Generate Token button to Get Access token.

You can copy the generated token and paste it into your Magento 2 Bitly settings configuration.