Build Error with ODK Aggregate

Hello everyone,

when I want to run aggregate in IntelliJ Idea, there is already an error with building it:

Build file '/home/elly/Dokumente/Hiwi DLR/aggregate/build.gradle' line: 20

Plugin [id: 'de.fuerstenau.buildconfig', version: '1.1.8'] was not found in any of the following sources:

When I want to run it with the Gradle Task AppStartWar, there is this error:

Could not set process working directory to '/home/elly/.gradle/daemon/6.1.1/odk-aggregate': could not setcwd() (errno 2: Datei oder Verzeichnis nicht gefunden)

My Gradle Version is 5.0, I'm not sure if it is the problem.

Does anyone know what the problem could be?

Thank you,