OS Catalina on Macbook Pro... Rekordbox won't open

Can anyone help?
I have not been on my Rekordbox for around 6 Months due to Covid (Not DJing at the moment)... My Rekordbox version is still on 4.5.0.0007 (old but solid)... I update my Macbook Pro to Catalina and my Rekordbox has stopped working, it won't even open... I'm hearing it could be because Catalina is 64bit versus 32bit... does anyone know if Rekordbox version 5 is 64bit? Thanks