it looks like you setup your database as a pluggable database (so a CDB is the container but you don't use it to store data, you must put your data in one of the attached PDB).
So in the RCU you must enter the connection details for your PDB. (I guess the defaults are orcl for CDB and pdborcl for PDB or something like that).
Google about Oracle multitenant architecture if you want more details about CDB, PDB etc. or ask to the person who installed the DB what are the connection details of the PDB (also maybe check the listener settings and you probably find out the details of the PDB).
Thanks Gianni, I just reinstalled the database by unchecking the container database option and now I can connect the RCU and create schemas.
Good news, with a multitenant setup it also work but you always need to make sure to connect to the PDB
One last thing for you: can you close the thread by flagging required posts? Right now it's still This question is Not Answered. and by closing it you will help others with same/similar issues.
I am not sure whats the problem. I dont see an option out here to mark it as 'Answered'.......