What does a data intermediary need to comply with?

Could you elaborate on the necessary compliance requirements for a data intermediary in the realm of cryptocurrency and finance? Are there specific regulations or standards they must adhere to, especially concerning data privacy, security, and the handling of sensitive financial information? Are there international frameworks or guidelines that they should be aware of? Additionally, how can they ensure that their practices are transparent and trustworthy, given the heightened scrutiny in this field?