1 Salesforce domain. 

Find the Salesforce domain in use. 

2 Trusted Origin folder.

In Okta administrator menu select Security/API and choose Trusted Origin folder.

Add the salesforce domain to the secure origins list. The result should look like the following.

The second NOT secure way ( can be used only for problem detection ).

In Okta administrator menu select Customizations/Other and scroll down the page.

Do NOT choose allow IFrame embedding. This should not be used in production.