BuddyPress registration and forum

I’m setting up a multisite website, on the main site of which I wanted to have BuddyPress and a Forum.

I installed Membership plugin first. Since that plugin has a rather primitive registration options and, after reading a few posts here, I decided to install BuddyPress.

Upon installation of BuddyPress:

a) I don’t see a Forum option/tab that is present on all the BuddyPress documentation I have seen so far.;

b) my new Registration page is completely blank (Registration is enabled on the site) and

c) I’m missing registration.php file.

I need a relatively simple registration form, which I later intend to link to the Membership plugin, but cannot do anything at this point.

Please let me know what might be the problem and how can I fix it.

Thank you in advance!