Once logged into the mambo EMM console navigate to Management > Policy Component.
Select Add Component and then make sure to select Applications as type. Then enter a unique name for the Component.
Once created, navigate to your Component in the list and select More then Configure.
Go to the applications table, click Add Application then Play Store then select Web apps from the menu on the left.
Click the + button on the bottom right of the page.
Enter the Name and URL then select the type of Display for the web app.
Finish off by adding an optional Icon if desired. Then select Create.
Google can take up to 15 minutes for the web application to upload. Once available open the app and click on Select.
This should bring you back to Applications Component with the Selected application in the list.
You can also click the Downward Arrow on the left-hand side next to the application & configure, check install status, etc.
Note: You will also have to make sure that Google Chrome is installed as part of the Application Policy Component for it to display in a Kiosk Mode.
Once you have your Application Component ready, you can create a Policy and Assign the Component within that Policy.