Incoming Emails are getting blocked

This is a sender side rejection, not a setting you can change in the receiving Outlook.com mailbox. Your screenshot shows the bounce came from Gmail, and the Outlook.com server rejected the message with 550 5.7.1 because the sending domain does not have SPF, DKIM and DMARC authentication records.

That means the person or system sending the mail needs to fix the domain it is sending from. I would ask the sender, or the administrator of the sending domain, to publish SPF, DKIM and DMARC records in that domain's DNS, using the exact values given by their mail provider, and then send a test message again. If the sender is using a custom domain through Gmail, the records must be set for that custom domain, not for gmail.com.

Adding the sender to Safe Senders in Outlook.com is unlikely to help, because the message is rejected by the Outlook.com server before it reaches the mailbox.

If you are the sender, I would check the details.txt file attached to the bounce message, because it should name the sending domain that failed. I would then fix the records for that domain with the mail provider that hosts it.