BuddyPress.org

You have to resolve permalink issue in WordPress before installing BuddyPress.
Apache Module mod_rewrite must be enabled for “pretty permalinks” so check with your webhost. Or, if you have access to the httpd.conf file, find #LoadModule rewrite_module modules/mod_rewrite.so and delete the # to uncomment it

Check out other WP configuration requirements before installing BP
https://codex.buddypress.org/getting-started/before-installing/#wp-configuration