How come when I try to get an app it says my Apple ID is locked?

There could be many reasons. Read these support guides:

If your Apple ID is locked or disabled - Apple Support

and/or

If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store - Apple Sup…

If you get no help, contact iTunes Store Support directly and explain your problem. Fill out and send this form:

iTunes Store - Contact Us - Apple Support

Regards

Giulio

Contact Apple Support at this link: Contact Apple for help with Apple ID account security - Apple Support

Regards

Giulio