You can add an image of the Instagram logo and link it to your profile URL. Our newer builder, Website Builder, has many social media icons including Instagram to add. Have you considered rebuilding your site in our newer builder?
I would definitely recommend checking out WebsiteBuilder. It has so many improvements and added benefits. All you need to do to get started is add a site to your account and you can play with it behind the scenes, not affecting any of your current sites. There also is no additional charge, feel free to check it out when you have a few minutes.