In Excel Office 365, I do not have the "Encrypt with Password" option
On Microsoft's website, it provides the following instructions to password protect an Excel workbook:
Select File > Info.
Select the Protect Workbook box and choose Encrypt with Password.
Enter a password in the Password box, and then select OK.
Confirm the password in the Reenter Password box, and then select OK.
https://support.microsoft.com/en-us/office/protect-an-excel-file-7359d4ae-7213-4ac2-b058-f75e9311b599
However, in my Office 365 version of excel, these are the only options I see:
How can I password protect this workbook?
Edit in response to the answer saying I should see a password option when hitting "Save As":
Then when selecting "More options..."
The documentation you found may be correct, but you are not getting the full menu that I get, as you are missing the "Encrypt with Password" option:
Try this alternative method: In the Review pane, group Protect, you will find a Protect Sheet button. This protects from change, but does not encrypt the document.
Press the button to show this dialog where you may specify what to protect and a password:
If this also does not work, ask your IT people why they have blocked all the options.