To create a mandala in infinite painter you can do this:
I took some screenshots on my phone
Create a new square document
Click on that icon
Click on setting
You can set the number of axes to have, many mandalas have 6, 8,10 or more axes, snowflakes have 6 axes, if you do flowers you count the petals, if flowers have around 6 petals you choose 6 axes. And the lock is there to lock that mandala guide in place, you can unlock it anytime and move it in another position.
Take the brush and a color and start drawing, you can zoom of course to see the details.
Draw a line to see what happens.
Now you can use any drawing mandala you see on YouTube to draw your mandala, you can start from center and build on that, think like how flowers are, dona tiny circle then add petals, then more petals on top of that and in time you can do it more an more complex