Wildbook times out after a period of inactivity, but doesn’t notify you when that happens. I don’t think this is the case here because your screenshot shows you logged in on the error message screen but I wanted to mention it as a potential reason this error pops up.
The second thing I’d like you to check is to verify that you’ve entered a username, an email address, and a temporary password for the new user.
I think there might be a restriction on Sharkbook that’s only letting site admins make new users. I’m not sure how long it’s going to take to resolve.
If you want me to create the new user for you in the meantime, send me a private message with their name, email address, desired roles, and orgs, and I’ll take care of it for you.