Will this work with WPMU Membership Plugin? I want to add

Will this work with WPMU Membership Plugin? I want to add a button to view programs I post daily.

I noticed when I installed a free theme off wordpress.org that my password field was not allowing anyone to register. Before I buy anything I want to make sure nothing will break.

this is the theme, I would like to install.
"GamePlan"

http://demo.cactusthemes.com/gpdark/

http://themeforest.net/item/gameplan-event-and-gym-fitness-wordpress-theme/5936266

Also this one:
http://ignitethemes.com/themeforest/switcher/?theme=evolution_wp