Need Help on Instagram Ads

I am new to social media marketing, I am trying to run an instagram ads for an institute.

This institute belongs to my friends mom, they approached me if i can help them to run ads for them.

They never run an ads on Instagram before. I am basically confused which ad objective should i use.

Running website traffic ad is of no use for them, they said me there business runs on lead people calls them for inquiry then their counsellor convert that lead.

So, i need call to action button on ad like CALL NOW .

Can anyone help me in this.