PHO/Java Development for API integration with 4PSA PBX Software

We currently use a PBX software called 4PSA (https://www.4psa.com/). We would like a developer to integrate with their API to create a user friendly web login so that our clients can retrieve their call logs, voice mails, turn on and off call rules and retrieve call recordings. The candidate will need to ensure they are able to download the free software and complete the integration where needed. We as the administrators will need to be able to add users to different organisation set within the 4psa software to grant different permissions to what the users can access for their organisation.