To ask admins for password, you also need to do this. There may be some other files also, which will need modifications. Likely in active.asp, topic.asp, search.asp. It will be similar though.
File: forum.asp
Lines 164-166
Find the following statements
if strPrivateForums = "1" and (Request.Form("Method_Type") <> "login") and (Request.Form("Method_Type") <> "logout") and ForumChkSkipAllowed = 0 then
result = ChkForumAccess(Forum_ID, MemberID, true)
end if
Modify as shown below
if strPrivateForums = "1" and (Request.Form("Method_Type") <> "login") and (Request.Form("Method_Type") <> "logout") then
result = ChkForumAccess(Forum_ID, MemberID, true)
end if