Yes, you can still use your Keepit username and password to sign in to Keepit even after you set up SSO. To be able to sign in with Keepit credentials, you need to select the Optional check box in the SSO configuration. If this check box is selected, then each time you sign in to Keepit you will have the option to use either your Keepit credentials or SSO.
Please keep in mind that if SSO is optional then you will not be able to take advantage of the convenience and security benefits of SSO.
When setting up SSO, we recommend you create an SSO Admin who will be able to sign in with his Keepit credentials even when SSO is not optional. The SSO Admin is a user role that does not have access to users or users' data but only to the SSO configuration. If you create this role then you can make SSO obligatory but always have a backdoor into the configuration in case SSO is misconfigured or the SSO certificate expires.
For a step-by-step guide on how to create an SSO Admin, see How to create an SSO Admin role