Please see the answers inline
1.Do the customer need to have their application to track the assets or aruba will provide the app?
Customers can create there application, if needed can get the meridian team help with creating one based on requirement.
2.If aruba meridian is the app provided then , is it a cloud based or we can use it as on premises application.
Aruba meridian is a cloud based solution
3.What is the use of aruba tag app? Is it only for device administration for label of devices or we can track the device by this as well.?
Aruba Tags are a key component of the Aruba Location Services portfolio and asset tracking solution.
The Aruba Tags Configuration App allows items to be easily tagged, regardless of where they sit.
You can refer to below document,
https://www.arubanetworks.com/assets/ds/DS_ArubaTags.pdf
4.How we need to integrate the Meridian with the aruba WLAN network.
If you have any solution document for complete setup please share with us.
You can refer the below document.
https://docs.meridianapps.com/hc/en-us/sections/360006480194-Configure-Aruba-Hardware