Install as usual addons... go to preferences, add-ons tab, install, pick the downloaded zip file.

You will find the addon in the TOOL tab on the right side of blender viewport.

Select the object you want to distribute. Keep attention the origin of the object is at the bottom so the clones stay on the curve. Keep attention the object is Z-up, know it will be replicate on its X axis. (Check the video tutorial if you don't know how to correct axis orientation)

then Shift select the spline

Use dupli Curve button

You collection option. This option will pick random objects from the first selected objects collection.

Be Careful with space parameter, because it means the space between pivot object. If you set a very small value, the number of instances tend towards infinity !

To scale the cones, select the curve, use TAB for edit mode, select all the control points the use ALT-S.

Note that you can scale points individually

in curve edit mode, Use CTRL-T on control points to bend clones orientation

Select the curve and adjust the settings.

Uncheck follow curve and update by using space or offset setting. now clones are always verticals even along a non planar curve.

You can always come back to this settings. You can finally convert everything to a mesh or singles instances