From Tamron:
December 20, 2018, Saitama, Japan - Tamron Co., Ltd. announces a new firmware update for the Tamron SP 150-600mm F/5-6.3 Di VC USD G2 (Model A022) for compatibility with the Canon EOS R and Mount Adapter EF-EOS R. The new F/W version makes the model compatible with Canon "EOS R" and Canon "Mount Adapter EF-EOS R" for general operations[1].
The lens firmware can be updated with the separately sold TAP-in Console. Customers may also contact Tamron USA's service department at 1-800-827-8880, option 1 for information on sending in the lens for the update.
Compatible Tamron Lenses as of 12/20/18[2]
[1] Functions used on DSLR cameras
[2] With the latest version of lens firmware