After detailed RnD and discussion with consultants, following are the options we have:
Option 1:
- Make a new domain in the AD
- Configure a new root OU
- Create a user having domain and AD admin rights
Option 2:
- Create a network admin user for both instances (db and app)
- Complete installation with an admin person at client who can use the admin user for CRM installation
The best case would be to get the Domain admin user but it's not that easy to get.