MYSQL version 8 uses Strong Password Encryption for Authentication by default.
The native MySQL access for WINDEV or WEBDEV supports this authentication method: caching_sha2_password authentication. You must, however, use a LIBMYSQL.DLL in version 8.0 minimum. Using an older version will cause an error: Authentication plugin 'caching_sha2_password' cannot be loaded.
You have basically two solutions:
1-Use the "Legacy Authentication Method". It can be done when installing the server:
Or using the MySQL WorkBench
2-Find the LibMySQL.DLL version 8.0 and copy it in the FrameWorkWin64X86 directory of WINDEV (WEBDEV). It can be found in the Lib directory of the MySQL server version 8.