Eu apenas baixei o projeto e abri. Aparece a seguinte mensagem no sublinhado de vermelho:
Project build error: Non-resolvable parent POM for br.com.alura:forum:0.0.1-SNAPSHOT: Failure to transfer org.springframework.boot:spring-boot-starter-parent:pom:2.1.4.RELEASE from https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced. Original error: Could not transfer artifact org.springframework.boot:spring-boot-starter-parent:pom:2.1.4.RELEASE from/to central (https://repo.maven.apache.org/maven2): Connection reset and 'parent.relativePath' points at no local POM