I just created a homebrew item. Nothing special about it besides it being tied to a spell. I have put the spell brackets in the description for toll the dead as well as tying it to the spell in the spells section of the item creator.

It is showing the following on the screen where I would publish the item: 

• This homebrew Item 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 Item.

I just created it and it is not currently in use anywhere. Does anyone have any thoughts on this? 

So "Licensed" content is D&D Official content, and Private Homebrew is that it links to an item you already made that isn't published.

Can you post the text of the item here?  Or a screenshot of it?

That being said, it being tied to a spell would do it.  Since that Spell has to be paid for, we can't assume that everyone has it.

Quote from Stormknight >>

The spell Toll the Dead is from Xanathar's Guide to Everything and is not available as part of the Basic Rules.

As above, the homebrew publishing system restricts content to that from the Basic Rules / SRD.

 Spells from EEPC are also acceptable.