To approve your Mac from your iPhone, you can follow these steps:

1. Click on System Preferences on your Mac.
2. Select Apple ID and enter your Apple ID and password.
3. It will now prompt you to enter the 6-digit verification code.
4. Using an iPhone that is already logged in to iCloud, open it and it will ask if another device is using iCloud and if it is allowed.
5. Tap Allow.

You can also approve your Mac using your iPhone or iPad by following these steps:

1. Go to the System Preferences on your Mac.
2. Click on iCloud.
3. Type in your iCloud id and password.

For more information, you can visit [Tenorshare](https://www.tenorshare.com/mac-os/how-to-approve-iphone-from-mac.html) or [Digital Care](https://www.digitalcare.org/how-to-approve-iphone/).