The above error indicates that the mentioned class may be missing from the Salesforce user profile.
The error may present itself when the user attempts to launch a Fen-X journey through Salesforce. The request button will be absent.
To investigate and troubleshoot this issue follow the below steps:
In Salesforce go to Setup > Profiles.
Select the Profile of the user with the issue.
Click Edit on ‘Enabled Apex Class Access'.
Assess whether the class indicated in the UI error is present in the ‘Available Apex Classes’ list.
If the mentioned class is not present for the user it should be assigned.
To enable the Apex class, select the class from the list ‘Available Apex Classes’ and press the Add button to add the class to the 'Enabled Apex Classes' list.