How to add owner

Hi yanliangcapgeminico,

you need to be an M365 admin to do this. (As you are taking over ownership of a team)
If you don't have access to the admin center you should contact your IT department and open a ticket.

There is one other choce if your company did setup the "Microsoft 365 ownerless group policy" (https://learn.microsoft.com/en-us/exchange/troubleshoot/groups-and-distribution-lists/ownerless-group-policy ).
In that case the most active users in that team got an email  with an actionable button that asked them to take over the ownerless team.
But if you or other team members did not get this email then you'll have to contact an admin.

Best Regards,
Sven