Hi! ODK-X Support has been removed from the latest versions of Aggregate (version number beginning with 2.x.x). The various versions can be found in releases: https://forum.odk-x.org/c/releases
Have you also considered using ODK-X sync endpoint? See: https://docs.opendatakit.org/odk-x/sync-endpoint/
Aggregate is a fairly short-term solution given that newer versions are not compatible, so we recommend sync endpoint.