Indeed, you won't be able to use the IDE (Code) tool of Telerik Platform, but you should be able to use the other Telerik Platform services (like Data, Users, Responsive Images, Email Notifications, Business Logic, Analytics) from within the web application. Unfortunately, there is no hosting solution in Telerik Platform.
Given that you can use the same backend API, you may create a web application with a technology of your choice (Telerik Kendo UI for example) and deploy it to a web server, for example, in your company's premises.
It appears that the web application will be used for administration purposes. I'd recommend that you familiarize yourself with the Security
and Administration API
concepts so that you make a more robust backend logic for both the mobile and administration apps.
Let me know should you have further questions.