I have two issues occurring with a subclass for warlocks that I am making. One says that it is too similar to the Celestial, but literally nothing resembles the Celestial in the subclass. The second is that I have information mapped from a private homebrew, but that is not true either. What am I doing wrong?

Also try hitting the save button on you homebrews. The checker only checks when save is clicked.

Thank you! That helped the similarity, but I am still getting the "This homebrew Subclass has data mapped to it that is licensed content or private homebrew. This typically occurs when licensed or private homebrew spells are linked to the Subclass." issue. Any thoughts?

Quote from BardicNCathardic >>

Thank you! That helped the similarity, but I am still getting the "This homebrew Subclass has data mapped to it that is licensed content or private homebrew. This typically occurs when licensed or private homebrew spells are linked to the Subclass." issue. Any thoughts?

 Any of the spells you assigned to it come from a book? That is the most common cause.

Yes, but they are linked through dndbeyond, so they should still be accessible, no?

Quote from BardicNCathardic >>

Yes, but they are linked through dndbeyond, so they should still be accessible, no?

 
You should only map things (like spells) to those that are part of free basic rules or free content like Elemental Evil.

You don't need to publish the homebrew to use it but if you do want to publish it then you cannot have modifiers/spells/etc mapped to licensed content that must be unlocked in the marketplace or to other homebrew.

I don't get why you are supposed to add a subclass feature for druids at level 3...it doesn't show that you get one on the druid table. 

Nobody gets it, it’s a stupid error on DDB’s part.

Quote from Androsofthewoods >>

I don't get why you are supposed to add a subclass feature for druids at level 3...it doesn't show that you get one on the druid table. 

 Because of circle of the land's circle spells. For that 1 subclass only, they get a feature at level 3 and while WotC has fixed it for later subclasses, they never errata'd the PHB one.

And because DDB told it's homebrew tools to check for a feature at every level the official subclasses give a feature, this bug (that is completely unrelated to the 4 year old thread it was asked about in) still persists.

Quote from DxJxC >>

Quote from Androsofthewoods >>

I don't get why you are supposed to add a subclass feature for druids at level 3...it doesn't show that you get one on the druid table. 

 Because of circle of the land's circle spells. For that 1 subclass only, they get a feature at level 3 and while WotC has fixed it for later subclasses, they never errata'd the PHB one.

And because DDB told it's homebrew tools to check for a feature at every level the official subclasses give a feature, this bug (that is completely unrelated to the 4 year old thread it was asked about in) still persists.

 
Except the Homebrew tool didn’t used to require a 3rd level feature for Druids, that got added later. So I still don’t understand why.

Quote from IamSposta >>

Quote from DxJxC >>

Quote from Androsofthewoods >>

I don't get why you are supposed to add a subclass feature for druids at level 3...it doesn't show that you get one on the druid table. 

 Because of circle of the land's circle spells. For that 1 subclass only, they get a feature at level 3 and while WotC has fixed it for later subclasses, they never errata'd the PHB one.

And because DDB told it's homebrew tools to check for a feature at every level the official subclasses give a feature, this bug (that is completely unrelated to the 4 year old thread it was asked about in) still persists.

 
Except the Homebrew tool didn’t used to require a 3rd level feature for Druids, that got added later. So I still don’t understand why.

 It's been that way for as long as I am aware of. The earliest references to it I found were from mid August 2018, so at least since the site's first year.