Unresolved plugin: 'org.springframework.boot:spring-boot-maven-plugin:2.6.6'

Question

I just created my first own maven project with IntelliJ and directly after setting it up I got these first two error messages:

Unresolved plugin: 'org.springframework.boot:spring-boot-maven-plugin:2.6.6' Unresolved plugin: 'org.apache.maven.plugins:maven-jar-plugin:3.2.2'

Does anybody know how to fix this? I have really no idea. The instructions that we got at university where not helpful at all...

By the way: Here is my pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.petra</groupId>
    <artifactId>Naehrwertangabenvergleich</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>Naehrwertangabenvergleich</name>
    <description>Naehrwertangabenvergleich</description>
    <properties>
        <java.version>17</java.version>
        <spring-cloud.version>2021.0.1</spring-cloud.version>
    </properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                   </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>