TOPIC:

Always error when try to set up mail trucks station dunno why.. anyone had the same problems?

Yeah... There seem to be some problems with the client code. N-Ice guys are working actively on it and they supply patched version like all the time.

Make sure you download the latest release / update from the Github location of the client. Hopefully things will get better...

Background: In 15.x the OpenTTD team introduced (again) a lot of changes. Which makes it difficult for communities to keep up with these changes. That's why it takes sometimes a very long time before we can upgrade our OpenTTD versions. The server controller needs to get updated to support the new version, the client needs to get re-created (which when there are a lot of changes is not easy), etc.
Now we are at a point where we kinda felt comfortable to upgrade, but on the client side things are still difficult to implement. But they are getting there!