Hi Tim,
If you are not already a member of the Beta group, you find it by selecting Groups below the PB logo at the top of this page. Request membership, and when you enter the group you will find download instructions and release notes for this second beta as well as the serial to extend the beta activation.
https://li360.pitneybowes.com/s/group/0F980000000H12mCAC/mapinfo-pro-v17-beta
Cheers,
Jon