Terminal returned "installation successful" but when searching for the folder Library/Applications Support/SIMBL it does not exist.
Does it mean it wasn't installed? Will I have to uninstall it or can I try to install it again as it is.
No errors were ever returned.
It's possible you were looking in the user library instead of the global library folder.
~/Libraryvs/LibraryYou should uninstall SIMBL and install mySIMBL*.
The original SIMBL has not been functional since Apple implemented System Integrity Protection.
* I am the developer of mySIMBL