Yeah this SSO error pops up a lot when the Salesforce/community account link gets messed up on ST's side, so honestly the fastest fix is just to log out completely, clear your browser cookies for st.com, then log back in and try creating the request again — if it still throws the error, open a normal browser incognito window and try from there since sometimes cached login sessions cause this; if none of that works you can't fix the Salesforce admin thing yourself, so just reply on that same forum thread or DM one of the ST moderators/staff there, they usually sort out the account linking within a day or two once you flag it.
