Hello,
How do I change the maximum failed login attempts allowed from the web (we've already set the brute force options)?
For this purpose, you need to configure password policies used in your AD domain(s). If you use Fine-grained Password Policies, see the following help article for information on how to edit Password Policies: http://www.adaxes.com/help/?HowDoI.Mana ... olicy.html.
If you don't use Fine-grained Password Policies, you need to set up the Default Domain Password Policy that is applied to the whole domain. For information on how to edit it, see the above help article. On step 4 of the article, select the Default Domain Password Policy and click Edit.
And is there an option to change the error message on the login-page?
No, it is generated "on the fly".