Why can't I make the tags, are they important fot linking the appKeys to Things?

Hi Jarmo, could you please specify what exactly you tried and didn't work? Are you trying to create tags programatically or manually from the ThingWorx Composer?

You can see tagging things as good practice as this would allow you to group different entities under specific project and so if you have lot of appKeys it would be easier to manage them with tag.