Dear Shayda Moyassari,
Greetings! Thank you for posting in Microsoft Community.
As per your description, it seems that you are trying to insert checkbox into Excel on Mac.
May I know if you are trying to insert checkboxes in Excel Online web app on Mac? If yes, we're afraid that currently the option is not available for Excel web app. We do understand the inconvenience caused and apologize for it.
For your reference: Add a check box or option button (Form controls) - Microsoft Support
Personally, I completely agree with you, this is indeed a good addition to the current experience for Excel web app. It would be definitely ideal if we could insert check boxes in Excel Online. We'd sincerely recommend you vote for this similar idea in Excel Feedback Community: Please have checkbox functionality for Web Excel · Community (microsoft.com).
Product Team is in-charge of the feedback site, and they are constantly checking the comments and feedback from our customer. Many features have been developed or improved based on users' comment.
Additionally, we'd recommend you using Excel client app on Mac as a workaround, we've also done a quick test on our side, and we can insert checkbox with version 16.71(23012902) using below steps:
If the scenario above is not consistent with yours, you can also post back and point that.
Your patience and understanding are highly appreciated. We hope that you are keeping safe and well!
Sincerely,
Rhoda | Microsoft Community Moderator