Q: How can I download apps or get the 3 months free trial music with no credit card

If you want to download free apps then what is currently stopping you from doing so ? Are you getting a message/prompt when trying to download an app ?

For Apple Music, to do the free trial you have to either have a card on your account when joining, or have a balance on your account that would cover the first renewal payment : Join Apple Music on your iPhone, iPad, iPod touch, Mac, or PC - Apple Support

You can use store credit to pay for your Apple Music membership, but you must have enough store credit to cover the amount of your first renewal. Learn how to add store credit to your account.