Hello @Rajkumar R
From the GUI, you will need first activate RDS license server then install RDS CALS.
Please check the Microsoft official document:
Activate the Remote Desktop Services license server | Microsoft Learn
Install RDS client access licenses | Microsoft Learn
If you are using ‘Web-Browser’ to activate your server, which means your license server does not have internet. You may try other connection method, if this one doesn’t work.
After active server then we can install RDS CAL
This article introduces some PowerShell script to install RDS CAL:
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.
Best regards
Karlie