Cannot use WP Smush Pro version configuration

I downloaded WP Smush Pro for website, but when I go in the Configurations section I cannot activate anything, because I still get the label "Try WP Smush Pro for free". I've installed WP Smush Pro manually or using the WPMU Dev Dashboard but the problem is still there in both cases. Can you please help me with this matter?
Thank you very much for your help.