Starting with version 3.5 User Profiles for Confluence is compatible with Confluence 9x only. See Atlassian's documentation about Confluence 9 for more details especially its breaking changes.
Introduction
On the following pages, you can find the complete documentation for this User Profiles for Confluence release.
The User's Guide is intended for anyone using User Profiles for Confluence. It provides you with information about the search and how to use the macros.
The Administrator's Guide is intended for Confluence administrators. It helps you to install the add-on, to add new profile fields, or to configure the synchronization with an LDAP.
The Developer's Guide provides you with a detailed REST API documentation.