XIBO Android client application by Spring Signage connect to XIBO and its a commercial product .
Is it possible to create a new android client application by someone using XMDS? Will creating such an application violate any license or copyright laws?
As long as the new player is entirely the work of the person authoring it (i.e. they haven’t tried to decompile the existing one, etc), then yes that is perfectly permissible.
Here is a good place to start for understanding XMDS: http://xibo.org.uk/manual-tempel/en/xmds.html