In case you use secure connection from ARIS Server to the users by switching from HTTP to HTTPS/SSL the default server name localhost is replaced by fully qualified domain name which includes the server name and the domain name.
A pure replacement like your example /ARISPortal is not provided within ARIS because its multi-tenancy concept includes tenant names in its URLs. Means, http://localhost/#default is the default value, but you may also have more tenants, like http://localhost/#test.
Moreover, ARIS supports deep links allowing you to use bookmarks pointing to specific pages, such as the User Management page: http://localhost/default/adminUsers.
As an unsupported and not update-safe workaround you could try to add a redirect instruction in ARIS' load balancer configuration (Tomcat web server) which allows you to use certain shortcuts like your /ARISPortal.
