Enrollment in CARES Act benefits is automatic and you DO NOT need to opt-in.
Applicable loan forbearance should be updated in your account with your student loan servicer, where you would normally go to make payments. Additionally, the auto-debit payment feature has been turned off until the end of the year. If you have already made a payment after March 13, 2020, then you can request a refund by contacting your servicer directly.
Find the official Department of Education guidance regarding all coronavirus relief efforts here. https://studentaid.gov/announcements-events/coronavirus