This is how I got it working:

1. Go to this web page: https://yacy.net/


2. On the upper side of your screen you can see "Download" and from there download the "YaCy for GNU/Linux"


3. After you download the archive extract it to your preferred location open the extracted folder "yacy" now here you can see "./startYACY.sh" file the easiest way to run this is just to open terminal and drag and drop this file into it and press enter. It will tell you that
   "YaCy started as daemon process. Administration" and an HTTP address just copy the address and paste it into the web browser


4. And one more thing for this search engine to run you will need java, you can find it in the software center I installed "OpenJDK Java 7 Runtime" but as far as I can know it will run on 6 as well.

All this can be done by running in a terminal:

sudo apt-get update

sudo dpkg --configure -a

sudo apt-get install -y openjdk-8-jre-headless

wget http://latest.yacy.net/yacy_v1.922_20191013_9964.tar.gz

tar xfz yacy_v1.922_20191013_9964.tar.gz

cd yacy

./startYACY.sh

Then open http://localhost:8090 in your web-browser.

Good luck