How to set AutoFocus on RGB camera? Captures are out of focus

After having succesfully used ML Marker Tracker API, which works very well with World Cameras, now i need for compatibility with other devices to stick with Vuforia Tracking.
The problem i'm facing is that the camera seems persistently out of focus. Vuforia has been set to Continuous Autofocus Mode, but seems unable to set it. So i'm trying to set it manually, for which i would use SetControlAFMode method. But i'm not understanding how to use it (pretty sure due to lack of competence with C# syntax).
How can i set manually and at runtime the different focus modes?

ps: i'm using unity 2022.3.9f1 with 1.5.0 ML OS and relative SDK (the one from january, i've not yet updated to the March update).

One thing I've checked: if I use the unity example from SDK 1.11 called CVcamera the preview is in focus. The strange behaviour is that if I make a video from the magic leap app capture, without having my application opened, the video is unfocused anyway.