You can easily insert any shape in Ludus. Refer to the following buttons located in your left menu or use the keyboard shortcuts : R (for rectangle) - C (for circle) 

Use Shift (⇧) to easily rotate your shape:

Use Alt (⌥) to easily duplicate it :

What parameters can I modify?

Find in your right menu all parameters that you can change towards your shape : color, stroke width, border radius and shadow.

"I did not find the perfect shape, arrow or line"

No worries, do not hesitate to refer to our stock images databases integration: Icons8, Iconscout and Noun Projet which you can find in your Smart Menu (⇥).

Apply the Color overlay so that the icon fits in your presentation.