Patches are only provided for .GA releases and not for any preview builds (alpha,beta, cr)
I would recommend you to upgrade to 6.4.0.GA first and than apply 6.4.6 patch for it.
However, I could only find the version jboss-eap-6.4-CVE-2015-7501.zip to download.
Is this version Red Hat JBoss Enterprise Application Platform - Version 6.4.0.GA or jboss cr version ?
That's for EAP 6.4, not for a community version.