Does OneCloud require any mandatory or optional attributes?
Aside from emailAddress (as part of the nameID format), there are no required attributes. That said, firstName and lastName will be used if they are included.
Does OneCloud support user provisioning through SAML? If yes, are there any attributes required for user provisioning?
OneCloud does not support user provisioning through SAML. There are plans to support this in the future, but we do not support it at this time.
Does OneCloud sign SAML request?
OneCloud does not sign the SAML request.
Does OneCloud support encryption of SAML assertion, NameID, and attributes?
OneCloud supports encrypted assertions.
Can OneCloud decrypt a document with an encrypted assertion?
Yes - OneCloud can decrypt a document with an encryption assertion.
Does OneCloud support SAML SSO flow on Android and iOS mobile?
Based upon your corporate device setup, SSO should work correctly via mobile web on Android and iOS devices.
Does OneCloud support app which can be installed on Windows and Mac machine? Does it support SAML SSO flow?
OneCloud does support both IdP and SP initiated sign-on flows.