Issue with Creating a Custom Character

I'm trying to play as a Druid from the circle of stars in a new campaign but when I level up using character manner, only choose and circle of land is available. I know that I will probably need to create a custom circle, but it is not showing up as an option when I try to level up. My DM is not super experienced, so we don't really know what to do.

Without the purchase of a compendium source, such as the Player's Handbook, you are limited to the freely available options of the SRD (System Reference Document), published by Wizards of the Coast as an introductory and freely usable subset of the rules. The SRD allows only one subrace per race and one subclass per class, one feat, one background, a generous selection of spells and monsters, but no art. I believe the Circle of Stars druid is in Tasha's Cauldron of Everything.

Thanks Keith! I was under the impression that I would be able to custom create a class in addition to the one subclass already provided. However, there isn't even a 'custom' option. Is this because of the SRD?

Back before Charactermancer was a thing, we just used to fill in stuff manually; this is still possible. But I just fired up a game under my  Dummy Account  which has nothing but the SRD. I see "Custom" options for both sub-class and sub-race. There is no custom top-level class or race option that I can see, but you could probably do a variant race by tweaking from "human"? And of course, for sub-class, unless you are playing cleric, you wouldn't see an option until using Charactermancer Level Up.