When you register on Instantgo, you pick a username which will be your unique identifier used on the platform.
This username is an easy way for you to let other people find you on the platform and connect with you. Your username will also determine the link to your public profile on the Instantgo website. For example if you username is "john" then your profile will be found at https://www.instantgo.com/john
You can edit your username on the Setting section and choose the one that you prefer as long as it is not being used by someone else on the platform and that it doesn't contain profanities or other unrecognized characters.
You username can also be used when you add sharing buttons on other platforms to let other users easily get connected with you on Instantgo.