Hi @Vaibhavi Rastogi
Do you want to install Windows Systms or Office?
Based on my knowledge, there are no LTSB versions of Office, but are LTSC versions, LTSC (SPLA) versions and others.
It's best confirm that which license of Office do you have? What are the error messages when installing and activating Office?
Besides, we only provide support through the Q&A forum and cannot contact you by phone or email.
If you want to open a ticket with Microsoft Support to help review your issue, please call the number of your range/country from link: https://support.microsoft.com/en-us/help/4051701/global-customer-service-phone-numbers.
Thanks for your understandings.
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