Thread: `No main manifest attribute, in filename.jar` after compiling a project in Github

It is first time for me to use Java script but I need to compile the following project in GitHub to implement some analyses.
This question may be too ambiguous to answer, but it would be helpful if someone could help how to run it.

github.com/p3et/dmgm
(please add https:// in front)

I am working under the following environment:
Windows 10 Home, version 22H2
Maven 3.9.3
java version 1.8.0_331
Java(TM) SE Runtime Environment (build 1.8.0_331-b09)
Java HotSpot(TM) 64-Bit Server VM (build 25.331-b09, mixed mode)
javac 1.8.0_331

At first, I downloaded zip file and opened it in Visual Studio Code from 'open folder', then `clean` and `install` the project under `demo` and `dmgm` folder under `maven`.
(I am not sure which folder is correct to run, but I tried both)

Somehow I could compile it and I found 'demo-1.0-SNAPSHOT.jar' was created in 'dmgm-master\demo\target' and `dmgm-master\target`, then I ran the file from PowerShell or prompt by the following script:
(Again I am not sure which .jar file to run, but I tried both)

cd [directory to the file]
java -jar .demo-1.0-SNAPSHOT.jar

However, it returned an error `no main manifest attribute`.
I have searched the reason and found that it happens as this project does not contain `manifest.mf`.
I understood that this file is used to specify the `main class` to start with the program.
However, there is no `main.class` anywhere in the folder.

I am stacking with this issue and looking for the right way to implement this repository.
Thank you in advance for your support.

Thank you for your advice and please wait for a while to confirm the files/scripts in the project folder.
I cannot make enough time to check it now but will do that.