Grey circles

[Gill8820]

I can’t open the next grey circles even though I have downloaded them.

[JammyDodgie]

Grey circles? Whats that?

[EL5tEL]

Have you finished the lessons that aren't greyed out? Typically finishing the available lessons will open a new set.

[Izim_M]

If you're talking about the skills on your tree, the grey color indicates that they are not available yet because you have to finish other -generally less advanced- skills first. Finish the last colored skills in your tree and the grey circles on the next row will become available.

[Thomas_kern]

you haven't unlocked it yet thats why