Multiple Login Prompts and Project Visibility Issue with Dual RM Installation under one host & Single JTS

We have installed two RM applications (RM and RM1) under a single JTS on the same Windows Server 2016 VM.

Setup details:
JTS and RM are installed in the same package group (APPGRP1).
RM1 is installed in a separate package group (APPGRP2) with context root /rm1.
* Each application (JTS, RM, and RM1) uses a separate Db2 database hosted on the same VM.

Issues we are facing:
1. The login prompt appears multiple times almost every time the browser is refreshed.
2. When navigating from an RM project area to RM1 (through personal dashboard), the RM1 projects are not visible and another login prompt appears.

Questions:
1. Is installing the Jazz Authorization Server with SSO required to avoid repeated login prompts and enable smooth navigation between RM and RM1?
2. If SSO is not mandatory, is there any other way to resolve this?