Bad UX for adding a user that is not in the address book to a group

request from Android user[*]:

When I try to add a new E-Mail address to a group, I get an input field with a checkmark next to it. After typing in an E-Mail address it looks like I now need to click the checkmark icon to add it. Clicking it closes the dialog without adding the new person to the group.

Current flow:

The actual workflow is to click the entry that is suggested in the list below after one typed in a correct e-mail address, which then gets a checkbox icon next to it and then clicking the checkmark icon at top. This workflow is not intuitive, as there is no obvious hint that the checkmark icon belongs to the whole dialog and not to the textbox.

Suggested flow:

Have a “plus” symbol next to the textbox, which then adds the address to the list (of possibly multiple new addresses) below. Have a “finish” or “close” button at the bottom instead of the top of the dialog, which is clearly meant for the whole dialog and not related to the textbox at top.
Possibly add a warning when the user tries to close the dialog when he entered an e-mail address at top, but did not add it to the list.