Taxonomy vocabulary not showing up as existing field in new content type
To use taxonomy with your content nodes, you have to add fields to your content types that allow you to assign taxonomy terms.
To add a field for your taxonomy to a content type:


Go to Structure > Content types.
Find the listing for the content type you want to modify, and then
click its manage fields link.
In the Add new field section, enter text for the Label and Name
columns.
In the Field type column, select Term reference from the drop-down
menu.
In the Widget column, use the drop-down menu to select from the
following widgets:

  Check boxes/radio buttons - The taxonomy terms are listed in a check box on the content creation page for this content type.
  Select list - A list of the taxonomy terms are displayed on the creation page for this content type.
  Autocomplete term widget (tagging) - A text box is added to the content creation page for this content creation page.


Selected or entered taxonomy terms are assigned to the content node when the node is saved or published.
Click Save.
In the Vocabulary drop-down menu, select the vocabulary you want to
use with this content type.
Click Save settings.


A taxonomy term field is added to your content type, using the label you chose. When you create content of this type, you will now find a field on the creation and edit forms that allows you to assign taxonomy terms to the content node.

Thank you.