There are several possible reasons for issues with logging into ApprovalMax:
First, check that you're using an up-to-date version of a supported browser
If you still can't log in, clear the browser cache and delete the cookies.
If the above doesn't help, add ApprovalMax to your browser's whitelist.
This is how it works for Chrome: open Settings -> Site permissions -> Pop-ups and redirects, then enter the approvalmax.com domain: