1Password application configuration for Single Sign-On (SSO) requires the Okta well-known URL field to be populated in the Okta Identity Provider configuration on the application side. This field will establish the SSO login between Okta and 1Password. Reference: Configure Unlock 1Password with Okta

• 1Password SSO Connectivity

Without this required field, the login will not be successful. 

Follow these steps to populate the required field:

1. Open a new browser tab or window and sign in to the account on 1Password.com.
2. Click Security in the sidebar, then select Unlock 1Password with Identity Provider.
3. Choose Other from the list of identity providers and click Next.
4. Select the Okta identity provider, then fill out the fields with its configuration information.
5. Click Next and populate the Okta well-known URL field with YOUR_OKTA_DOMAIN.okta.com/.well-known/openid-configuration .

From 1Password documentation:
 
If assistance is required in how to configure 1Password with Okta, please review the following documentation: Configure Unlock 1Password with Okta.