@BallScrewBob: IDE is 1.8.5, per the topic. 
@pert: Good information! Thanks! I didn't see any more detailed info in the console output but maybe I'd missed it.
I resolved the core issue (not the CRC one, but per pert we don't need to, so that's very helpful to know.) Looks like we didn't read the Adafruit page closely enough (it's an Adafruit Feather M0 Adalogger) and there are more directions (an entire detailed guide, in fact) on their website. Once we pored through again more closely (and had slept on the issue) we found it, followed it, and are all set.
Thanks for everyone's help!