• Download BuddyPress Limit Friendship request
• Extract bp-limit-friendship-request-x.x.zip(where x.x is version no)
• Upload bp-limit-friendship-request to wp-content
• Activate BuddyPress Limit Friendship request by visiting Dashboard->Plugins->Installed or Dashboard->NetworkAdmin->Plugin->Installed(if you want to netwrok activate it)
• Visit Settings->BuddyPress->Settings and update the criteria. 
• Enjoy 🙂