How to create user for connect to database

Question

ERROR :
[FATAL] [DBT-05509] Failed to connect to the specified database (cdb21).
   CAUSE: OS Authentication might be disabled for this database (cdb21).
   ACTION: Specify a valid sysdba user name and password to connect to the database.

First step:

./runInstaller -silent -responseFile /scratch/app/user/product/21.0.0/dbhome_1/install/response/db_install.rsp \
oracle.install.option=INSTALL_DB_SWONLY \
UNIX_GROUP_NAME=oinstall \
ORACLE_BASE=/scratch/app/user \
INVENTORY_LOCATION=/scratch/app/oraInventory  \
SELECTED_LANGUAGES=en \
oracle.install.db.InstallEdition=EE \
oracle.install.db.isCustomInstall=false \
oracle.install.db.OSDBA_GROUP=oinstall \
oracle.install.db.OSBACKUPDBA_GROUP=oinstall \
oracle.install.db.OSDGDBA_GROUP=oinstall \
oracle.install.db.OSKMDBA_GROUP=oinstall \
oracle.install.db.OSRACDBA_GROUP=oinstall \
SECURITY_UPDATES_VIA_MYORACLESUPPORT=false \
DECLINE_SECURITY_UPDATES=true

Second step:

dbca -silent -createDatabase                     \
-templateName General_Purpose.dbc                \
-gdbname cdb21                                   \
-sid cdb21                                       \
-responseFile NO_VALUE                           \
-characterSet AL32UTF8                           \
-sysPassword Welcome1                            \
-systemPassword Welcome1                         \
-createAsContainerDatabase true                  \
-numberOfPDBs 1                                  \
-pdbName pdb21                                   \
-pdbAdminPassword Welcome1                       \
-databaseType MULTIPURPOSE                       \
-memoryMgmtType auto_sga                         \
-totalMemory 4096                                \
-storageType FS                                  \
-datafileDestination /scratch/oradata/           \
-emConfiguration NONE                            \
-ignorePreReqs

Answer 1

Start The service using :

lsnrctl start

Then :

startup