read my previous post - fixed it by my own.
need install Bind DNS server - without this all will be ruined. then DKIM generates automatically (i firs installed bind dns, then created website), then with cloudflare extension just sync all records 1:1 to cloudflare, and make proxy required records in cloudlfare. it sincs all required dns and dkim records also.
if need DNSSEC security, don;t install in plesk if using cloudlfare. just generate in cloudflare dns setting this record and fill form in domain name registrar (etc hostinger), wait 10 minutes. till successes. then you can issue lets encrypt ssl free certificate with all box checked..
thank you for attention.