In order to update the package, you need to do it through the app exchange.
Click on “Get it now”. You will be prompted to login, which you will do with your Salesforce account.
If you have several environments, you will be asked to choose if you want to install in prod or in a sandbox environment. Select the right environment and login again with those credentials if necessary.
From here you will have an “Upgrade” button to upgrade the package.