djay 4.2.1 will not download via App Store... message: "An error has occurred"...HELP Please!

Had djay 3 (installed with disc, 3 or 4 years ago).Recently, MacBook Pro problem (could not restore) caused loss of djay 3 app. Could not find my djay disc, so I found djay app again online & installed it…Demo version was installed, so I paid for it (not through app store) via paypal. I thought I purchased newest version of djay. I got djay 3 again updated version & an email with djay 3 License key. I clicked onto djay app icon to type in License key, but djay was already installed. I originally wanted to install the newest & latest version of djay 4.2.1… so I purchased djay 4.2.1 through app store (began to download after signing in Apple ID & password). Cannot download djay 4.2.1… so I check into App Store, under “Purchases” and I find djay under “Other Purchases” , stating, “An error has occurred”.

PLEASE can someone or anyone from Algoriddim help me fix this problem???.. Do I need to to de-activate or delete the older version of djay 3?..Summary: I unnecessarily paid for djay 3 version, so I paid for djay 4.2.1, the newest & latest version and this is not downloading through App Store (with error message)… PLEASE HELP?