The bandwidth required will depend on how many users you’ll be supporting remotely, what applications they will use (Power Point, PDFs, video file are heavy…).
The main factor is latency. For a “desktop-like” experience, you should keep lattency below 150 / 200 ms. Above this, you’ll start to experience delays in mouse clicks and screen refreshes.
There is NetLimiter that can provide you 28 days fully working trial to do some tests based on your scenario.