If your first problem has already been encountered by other users, checking issues may avoid you to search the problem on your side but shows directly that the software installation is not good at all (and it seems).
error: variable or field 'controlEvent' declared void In function 'void setup()': In function 'void draw()': At global scope:
on Processing development platform, you load an example, change some parameters (number of your serial port where the Arduino board is connected), then run the software on your Mac
In fact, *.pde comes initially from Processing, and Arduino kept the same extension rather than calling it for example *.ade (as pde means Processing Development Environment). It seems now too late the change the extension (see Arduino website on pending issues).
Whatever, it is the normal way and even if the author of Arduinoscope did some mistakes in the packaging of its software making it uneasy to use for a beginner, it is quite usual and you must prepare to see same issues on several other software (even mine I must admit due to lack of time to check if all libraries are packaged with, if all version of software compiles). Arduino and Processing are made for "quick prototypes" and amateur hands-on experiments..
Max sample rate - 5M/s (AUTO mode)[ch65292]8 bits