Hi,
Problem Solved !
I asked to my colleague, to install "Workforce" on our enterprise portal, and after trying to create a workforce project, he had the same error "failed to create the Feature Class.".
He inspected the logfiles in ArcGisServer Manager and he saw this error. After activated the debug mode and retried he saw "failed to create the Feature Class : datastore is read only." or something like this.
After searched on google, he saw that when there is less than 1go of free space on portal's hard disk, datastore pass in read only.
Just before trying "Survey 123 Connect", we had an issue with disk free space following a tile cache generation… so we think that our datastore changed of status at this moment.
After changed in writing mode, "Workforce" can create project and "Survey 123 connect" too !