I followed the instructions on https://github.com/blynkkk/blynk-server
Install the Java SE 11 but don’t install the latest Java runtime. It will result in an error, like in your screenshot.
After that, setup mail.properties and server.properties, both of which should present during first .jar execution. If you already executed it, delete everything in the folder except the .jar, and both .properties. Execute again. If it still doesn’t work, edit the server.properties and change the “https.port=9443” to 8443. Try to create a new account using the phone. It worked for me, but everytime i turn off my computer it happens again.