I have created a simple application in Apex instance in Oracle cloud always free tier and added a workflow which contains email sending function. However, when I click the button which initiates the workflow, it throws error as follows.

Does anybody have an idea about this error? Do I need to grant any privileges to the apex user?

  is_internal_error: false
    original_additional_info: ORA-01031: insufficient privileges
    ora_sqlcode: -1031
    ora_sqlerrm: ORA-01031: insufficient privileges ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 5232 ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 3530 ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 3446 ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 5212 ORA-06512: at "APEX_240100.WWV_FLOW_PROCESS_NATIVE", line 1142 ORA-06512: at "APEX_240100.WWV_FLOW_PROCESS_NATIVE", line 1966 ORA-06512: at "APEX_240100.WWV_FLOW_PLUGIN", line 4275
    component.type: APEX_APPLICATION_PAGE_PROCESS
    component.id: 9428239518565545
    component.name: Initial Inquiry Workflow
    error_backtrace:
    ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 5232
    ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 3530
    ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 3446
    ORA-06512: at "APEX_240100.WWV_FLOW_WORKFLOW", line 5212
    ORA-06512: at "APEX_240100.WWV_FLOW_PROCESS_NATIVE", line 1142
    ORA-06512: at "APEX_240100.WWV_FLOW_PROCESS_NATIVE", line 1966
    ORA-06512: at "APEX_240100.WWV_FLOW_PLUGIN", line 4275
    ORA-06512: at "APEX_240100.WWV_FLOW_PROCESS", line 192