Some 'private browsing' modes clash with Educa's security settings, which will make it difficult for you to log in and use the system. This is especially true of mobile devices. You will need to switch to normal browsing mode to log in.
This is related to our site's security, so at this stage it's not something we are going to be able to change from our end. Instead you'll need to turn 'private browsing' off.
Here is Apple's explanation on how to turn Private Browsing on and off for your iPhone or iPad: https://support.apple.com/en-nz/HT203036
If you are not using an Apple device you will need to look up the specific instructions for your device/browser.