Login to your BitGo dashboard (test or production environment) and go to your account settings.
BitGO dashboard
Obtain your BitGo enterprise ID.
Open Developer Options and click on Add Access Token to obtain your access token.
BitGo Developer Options
BitGo access token form
Fill in the form with your access token label, validity period and server's IP Address. Set to the maximum possible validity period unless you want to specify otherwise.
Set the Lifetime spending limits of each supported Cryptocurrencies (required)
Check the Permissions: View, Spend, Create Wallets, and Full Administrative Access.
Next, Click on Add Access Token. It will be displayed to you ONCE after successful creation.