18.104.22.168 is not certified with Linux 6.x - you will need a minimum of 22.214.171.124 - Oracle&reg; Database
I would suggest using Linux 5.9
A bit bizzare that you can't pick up some skills on your job which can be useful for the job later!
Adding to Srini's contribution,Below are the links that helped me setup 12c RAC on my pc (work pc as it' got 1tb disk and 8gb memory).
I tried getting it installed for weeks due to not finding a particular note that applies to me specifically. However, combining these 2 notes helped me to achieve it. It could be helpful to anyone else if not you. The links are:
Even though, it is for 12c, I reckon it applies to 126.96.36.199 as well. For older releases, check the oracle-base site which has always been of immense help and inspiration.