The node Random is funny in this respect.
On the one hand it can return a single constant random value, but on the other hand it can return a whole range of random values, depending on the case in which it is to be applied.
If you look closely, you can currently see diamond-shaped outputs on your node.
Simply put, these outputs give you as many randomly generated values as the number of points in your mesh.
However, the node Transform requires a single value, since it treats the points as a whole object and does not look at each point individually (Set Position would, however).
In this case you would just have to pass an integer value into the ID input of the Random node, and it will switch to a simple output (circle instead of diamond).
