Is this plugin compatible with multisite?

Yes, Advanced Database Cleaner is fully compatible with WordPress Multisite.

In a multisite network, only the main site (network administrator) is allowed to scan and clean the database, including orphaned items across the entire network. Sub-sites cannot perform cleanup operations.

This restriction is intentional. Database cleanup is a sensitive operation, and we ensure that only the super administrator, the person responsible for the entire network, has permission to execute actions that affect all sites. Your database is important, and the plugin is designed to keep it protected and under your full control.