Can I track my lost macbook without "findmy" app??

If you set up Find My on the Mac before it was lost, you can log into your Apple Account on any other computer or device capable of browsing the Internet:

https://www.icloud.com/find

and try to track it. It doesn't require the actual Find My app.

If you didn't set up Find My first, then as D.I. said, there will be no way to track it.

Regards.

No. Can't do that.

Find My has to be set up with the computer in hand.

Set up Find My on your iPhone, iPad, or Mac - Apple Support