First step:
Open file /src/application.properties, check similar bellow code: spring.datasource.url=jdbc:mariadb://localhost/db_name?user=root&password=123
First of all, create database name [db_name], sure your user and pass is correct. If your user has no pass, just remove "&password=123". That's all.
Import to eclipse as Maven project.
Update maven.
Run on tomcat >= 7.
Commnad build .war file:
mvn clean package