If you're not an administrator of your Mac, you can be prevented from installing and updating software as well as making certain changes to your computer.
Being a "standard" user is good security practice, but sometimes you need admin access. Here's how to temporarily elevate your privileges to admin status.
From the Dock, click the "Padlock" icon or otherwise launch the "Privileges" App.
When prompted, enter the reason you need admin access and then click "Request Privileges."
You'll then be prompted to enter you password or fingerprint
Once you authenticate, you'll see the Privileges App will change color, show as unlocked and have a number badge. This number indicates the number of minutes you're granted admin access for.
Once your time expires, you'll receive another notification indicating your privileges have reverted to standard.