Checking the safety of Lu AF28996

Key Inclusion Criteria: * The participant is Chinese, defined as having four Chinese grandparents being born in China. * The participant is diagnosed with idiopathic Parkinson's disease (consistent with the United Kingdom PD Society Brain Bank Criteria for the Diagnosis of PD). * The participant's Modified Hoehn and Yahr score is ≥2 and ≤4 (in OFF) and ≤3 in the ON state. * The participant experiences well recognizable and predictable motor fluctuations in the awake time including predictable morning OFF episodes causing clinically significant disability during the last 3 months prior to screening, as evaluated by the investigator. Key Exclusion Criteria: * The participant has received oral or transdermal dopamine agonist treatment ≤4 weeks prior to screening. * The participant has undergone a neurosurgical intervention for Parkinson's disease (such as pallidotomy, thalamotomy, foetal or stem cell transplantation or deep brain stimulation). * The participant has any other disorder for which the treatment takes priority over treatment of Parkinson's disease or is likely to interfere with trial treatment or impair treatment compliance. * The participant has received Traditional Chinese Medicine treatment ≤4 weeks prior to screening. Note: Other protocol-defined inclusion and exclusion criteria may apply.