Arbortext 5.4 and earlier used a completely different licensing software called "ELAN". The concurrent licensing server software was called ELAN License Manager. However PTC no longer supports or distributes Arbortext earlier than 6.0 so you will find it very difficult to download such old software. Instead you should look at using a currently available version such as 6.0, 6.1 or 7.0.
BTW I've heard of people who were able to get Arbortext 5.x working under Citrix with fixed licenses but use of such a configuration is likely to be in violation of the software license agreement.