Is the owner of an audio social media platform sinful if members upload musical files or Christian hymns to it, especially given that it may be difficult to control the content as the number of users increases?

The owner of a website is primarily responsible for what is published on it, and he must prevent content that is religiously prohibited. If he cannot prevent forbidden materials, then he is not permitted to create the website. He risks incurring the sin of what is uploaded to it, because he has assisted in the dissemination of forbidden things. Allah the Almighty has forbidden cooperation in sin and aggression. It is stated that assisting in disobedience to Allah is forbidden. Merely placing a warning not to upload forbidden materials is not sufficient. The obligation is to create a mechanism to prevent forbidden materials; otherwise, he should refrain from creating it. Whoever abandons something for the sake of Allah, Allah will compensate him with something better.