Thank you for posting this in Microsoft Q&A.
I understand that you want to activate security defaults in your tenant. however, it appears that your tenant is still listing two conditional access policies.
With global administrator permissions you can be able to delete existing conditional access policies that you have configured earlier. You can't modify existing policies if you don't have premium license.
Try to remove the current policies. If you are still facing issues, please share the conditional access policies that have been enabled in your Tenant.
Hope this helps. Do let us know if you any further queries.
Thanks,
Navya.
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