Your admin will add SmartDraw as an app available for your Team instance from the Microsoft Teams App Store. Click here to get SmartDraw for Teams.
Select Apps in the bottom left panel of your Teams instance.
Search for SmartDraw.
And Add to install the SmartDraw Teams app.
To add SmartDraw as a tab in a shared channel, click to Add a tab and search for the SmartDraw app on the new tab.