Currently you can not add resources through a remote Database or through the Cloud/APFW web page.
The only way to add "Resources" to an activity is to have access to the main database on the server.
This may have been overlooked as it is such a small area of Act, but as the only current way to add items, is to email Act technical support and ask them to add your list of Resources creating a delay and extra work for the Cloud Techs.
To see this go to "Schedule>Manage>Resources."
I have attached screen shots to show the current limitations in both Cloud and Remote databases.