Take Debian for example.

1. run apt update
2. run apt install default-jre openjdk-8-jdk ant zip (install java, ant, and zip)
3. run wget https://github.com/yacy/yacy_search_server/archive/master.zip (the latest version of Yacy)
4. run unzip master.zip
5. run cd yacy_search_server-master
6. run ant clean all (compile Yacy)
7. run ./startYACY.sh
8. run cd bin
9. run ./passwd.sh newpassword
10. open the http://your vps's ip:8090 in your local browser, and log in as admin with newpassword.