Usage

To use Beta Quad,

Switch to Blender Edit mode, select the faces, then right-click > Context menu,

Select Beta Quad from the bottom of the menu.

There are few parameters on the Left-Bottom menu : 

Quad size : it define the quad size of the result. Smaller quad will be slower.

Size Multiplier : it can be used to change the quad size slowly. Its value will be reset every time you use the tool.

Inset Boundary : It add the supporting edges at the boundary. It will make the mesh boundary looks sharp when sub-divided.

Inset Width : the width of inset

Inset sharp angle : It defines the max limit angle for sharp boundary edges

Keep Sharp edge : this option is used for turn off smoothing for sharp edges. It preserve the overall shape of the mesh

Edge Angle : it define the angle of "sharp edge". Angle smaller than this number will not be smoothed.