You can share your diagram with others even if they don't own SmartDraw by sending them a link. To get the link, go to the Home tab and click on Share.
Select "Copy Link".
You'll get a dialog where you can choose whether the person you send the link to can just View or both View and Edit your diagram.
Pick the option you want and click on "Copy Link" to copy the link to your clipboard. You can now email that or put it in a chat program like Slack.