I just added Membership plugin and I get "undefined index" errors. What am I doing wrong?

I bought the Membership plugin from AppSumo yesterday and installed it. (I also installed WP Dev Dashboard plugin, but that doesn’t seem to be a problem.) When I activate the Membership plugin, I get this error message on the admin page: “Undefined index: HTTPS in /home/public_html/wp-content/plugins/membership/membershipincludes/includes/new-pointer-tutorials.php on line 288”

On the site itself, I get two “undefined index” errors:

1) “Notice: Undefined index: subscriptions_page in /home/public_html/wp-content/plugins/membership/membershipincludes/classes/membershippublic.php on line 2010

2) Notice: Undefined index: registrationcompleted_page in /home/public_html/wp-content/plugins/membership/membershipincludes/classes/membershippublic.php on line 2097

Any suggestions on how I can fix this?