Toad - ORA-28040 Error


I am new to database and Oracle business. So I apologize in advance if my question is simple. I installed Oracle 193000_db_home on a Linux computer with Centos 7 operating system. I have created users without any problem and Oracle is running. I installed both 16.1 and 13.3 versions of the Toad for Oracle program on my Windows computer. I copied the tnsnames.ora and sqlnet.ora files from the /u01/app/oracle/product/19.3.0/dbhome_1/network/admin file path on my Linux system to the C:/oracle/instantclient file path on my Windows computer. When I opened Toad, version was normally displayed in the "Connect Using Oracle Client" section. I tried downloading both versions 19 and 21 of Instantclient from the Oracle site, but the error did not change. Can anyone help with this issue?

Additionally, if I don't select "Connect Using Oracle Client", I can login. But I need to login using Instant Client.

I added the hostname and IP of my Centos 7 Oracle Database server to the host file of my Windows server. I can ping both by hostname and by IP.

Best regards.

You might want to take a look at SQLNET.ALLOWED_LOGON_VERSION_SERVER parameter in the following 19c documentation: