For Śatruñjaya’s main temple, there is no standard Jain historical record that names a 6th-century builder. The main temple is dedicated to Ṛṣabha/Ādinātha, and a scholarly study notes that the current main Ādīśvara Temple was completely rebuilt in the late 16th century, while the earliest non-mythical construction is usually dated much earlier. ( jainpedia.org)

So, if you heard “6th century,” that is likely a confusion with another period or a traditional legend rather than the accepted history of Śatruñjaya. ( jainastudies.soas.ac.uk)