For the teleport script, it will only work on a local script because this.world.getLocalPlayer will return the server player I believe on a default script. It's best to use a trigger to test this to get the player reference. Also make sure you have custom player movement turned on in player settings.
It is kinda a confusing name because there is a teleport function on spawn point but this sets the players position directly.
For the attach one. Same as the other. get local player only works on a local script. Also make sure this script is attached to an entity that is set to be attachable. Also make sure the entity is collidabe. To get the player reference for this I would do it on grab start.