OK so have just endured the same issue where the other fixes were not working.
Did the “Ctrl Click” on the app and Get Info then ticked the Override Malware… and bingo… opened up straight away. I gotta say though… doesn’t feel quite right to be doing that but it has got it working so happy about it!
Thanks to all those trying to help 
Well, if you get involved with building drumkits it WILL damage your computer, as it creates hundreds of megabytes of useless nested folders of wav files. If you have 256gb Mac mini, it’ll fill up that HD in no time.
Hey it did work on step 1 and 2 can you send me step 3 please
Step 3 is posted above. There are other users that have also posted what they said worked for them and I suggest you try those items before you try the 3s option.
Let us know if any of these options or steps works.
