New users trying to log in with SSO, getting error message

I work for a company that just acquired another small company. The employees at this company are using mostly personal devices.  One user has been trying to log in, but is getting the following error when he tries to log in through SSO:  

Something went wrong while you tried signing in with SSO. To further troubleshoot the issue, please contact your admin and provide the following tracking ID.

WEB_bcc44a591105b5ba0ac2a5b830a1b9ff.

We tried manually creating an account, but logging in with that produced the same error. I'd love some insight on what might be causing this, and how to fix it.