Single logout idp (octa) -> sp.

Hello, I would like to know how to carry out a single logout process when the initiator is okta. My client is an application that uses spring-security-saml. At the moment when the logout is initiated by SP (my client) everything goes well - it is logged out of the application as well as from okta. However, in the case when I log out first from the okta, the client is still logged in. How okta should know to which endpoint should send LogoutRequest ? The configuration only has a field Single Logout URL but it’s location where the logout response should be sent.
Thank you in advance for your help.

When we tries to send LogoutRequest from SP. We are getting status as AuthFailed due to Invalid Signature. We doesnt know what went wrong in SAML message signing?