How to obtain adult norms for Raven's progressive matrices?
You would need to obtain a copy of the test manual. It includes norm tables for different groups.

If you Google it you might be able to find out where to purchase a copy

Equally, many psychology departments have test libraries and they are likely to have a copy.

It's also possible that some journal articles that have used Raven's could provide a rougher approximation to actual test norms.