NIST has released four introductory training courses for the 800 series of special publications that make up the basis for the NIST Risk Management Framework. Each 60 minute course does a great job covering SP 800-37, 53, 53A, and 53B. If you need a leg up on the knowledge that forms the basis of CMMC training, you should check out the courses.
NIST Training Courses:
NIST CPRT: https://csrc.nist.gov/Projects/risk-management/rmf-courses