Remote.It doesn’t support Minecraft or Terraria as service types. You can set them up as generic TCP or UDP services and it should work.
The error message you are receiving on remote.it when trying to connect on the UDP service set up indicates that Remote.It cannot detect that the UDP service is not found. You should make sure that you set up the UDP service with the port 19132 and not the Minecraft TCP port. I believe you need both TCP and UDP services. See this post. How to use both TCP and UDP on the same port (19132) for Minecraft Bedrock with remote.it?