I’m trying to link my iPhone to my Mac to use mobile internet on my Mac and it wont work

Do you have the HotSpot feature available with your cellular service plan? If you are not sure then check with your carrier. This is important because if the HotSpot feature is not activated by your carrier then nothing will work.

Open Settings on your iPhone and select Personal Hotspot. Simply turn this feature ON. If you do not see Personal HotSpot in your settings app then it is not available to you from your carrier.

Axel F.

Hotspot is carrier specific feature. Contact your Carrier (Cellular Service Provider) The agency who issued the SIM to you and ask them if they have enabled it for you.