That link actually re-directs you to a Single Sign On portal within School Messenger's website.
When attempting to log in you are getting an "Authorization Failed" message.
School Messenger is aware of the problem, have identified that it is related to Chrome and are working on a fix.
In the meantime you can do at least two different things.
- Use another browser
- From Powerteacher Pro, go to Apps on the left, and select School Messenger. That will take you directly to School Messenger using the Single Sign On. From there you will be able to use School Messenger.
If you are really daring, you can try this
Have the customer Open their Chrome Browser.
- In the address bar type chrome://flags
- Search for "SameSite by default cookies"
- Change from "Default" to "Disabled"