I use magmi 0.7.23-git, and Magento Enterprise 1.14.2.1.
When I install Magmi and try to access /magmi/web/magmi.php I see Apache's plain text authorization request. "magmi"/"magmi" and magento login credentials don't work.
How I can solve that problem?
if you just installed magmi and your getting "You must be logged in to use Magmi" error message. Try login in with "magmi" for both username and password. on Magmi github page it states
Authentication
Following previous issues with the mis-use of Magmi in an insecure way, Magmi now contains built-in authentication. Once you have provided DB details and Magmi can connect to the DB, you will need to login using a set of Magento admin credentials to use Magmi. If Magmi has not yet been configured to connect, then the username and password are both 'magmi'