The issue here is that you did not select the 'Active Directory Integrated' version of Passwordstate when you installed it, instead you selected 'Forms-Based' Authentication. So we have two options here:
You reset the installer, and install again - https://www.clickstudios.com.au/community/index.php?/topic/1663-resetting-the-passwordstate-setup-process/
Or you download this document and migrate from forms to AD - depending on whether you have much data in the system, the option above might be quicker - https://www.clickstudios.com.au/downloads/Forms_to_AD_Migration.pdf
We hope this helps.