I don't know what other options Zoho have but it looks like Zoho can act as a SAML identity provider if you have Zoho One or Zoho Vault Enterprise.
That's what I'd like, but we don't have either of those and neither does the client in question.
IDaaS providers such as onelogin are not ultra cheap. I think SSO+MFA is going to be $4/user/month.
But then you have support for SAML and OpenID Connect for unlimited apps as well as hardware tokens, OTP, APIs and the works.
Yeah, that might defeat the overall purpose. That adds up really quickly when it's just for a wiki.
True, but don't they use mail or any other service?