Step 1: Download the Office Deployment Tool :

For Office 2016 ProPlus : 

For Office 2013 ProPlus: 

Step 2: Extract this tool on  RDS server.  Use command prompt with  "Run as admin" option

Step 3: Create a SHARED folder on your server

For  example “C:\data”  and make sure you have full permissions to the folder. 

Step 4: 

Edit  “configuration.xml ” file, copy the below script and paste it into the file. Change the Host name_of_PC to the host name of your own server. Save the configuration as “configuration.xml” 

Step 5: Run the following command from an Elevated Command Prompt, in the file location where you extracted the tool you downloaded.

Below command will save the full Office setup offline in "c:\data"

.\setup.exe /download configuration.xml

Step 6: Run the following command from the same Elevated Command Prompt:

.\setup.exe /configure configuration.xml

 Office 365 ProPlus will be installed on your RDS server.

Step 7: Completed.

Once   user logs into the RDS server , they will now be able to use Office 365 on your RDS server.