Not Able To VNC To Kali Machine Using Cloudron And Guac

Hi, I have set up my kali linode already, and successfully set up guac via cloudron. Adding SSH connections on guac works now, but the VNC is not working.

I have inputted the same username and password for VNC connection, when setting up the kali linode.

However, i'm still stuck on the 'connected to guacamole, waiting for response…' page.

I have verified that port 5901 is running VNC, but somehow i'm still unable to connect. Kindly provide your expertise guys, thanks :)