1.5 is a double value whereas 4.5f is a float value. Random range takes two floats not a double and a float. Try using 1.5f. Note that compile errors are C# language errors and not Unity errors so you can find plenty of info by searching for those error codes.
A couple of extra things; the 2D forum is for discussions on 2D features. What you’re asking is a general scripting question more appropriate here. Also, when posting code you can use code tags for formatting rather than plain-text.