I purchased two Gotham Steel 9 and 1/2” pans. I use an induction cook top. This was a match made in hell. Didn’t realize that I needed an interface between the cooktop and pan. What would be the best direction to take?
It's possible to use a pan that does not have magnetic steel on an induction cooktop, but it requires as you note an interface - meaning, a piece of magnetic metal that will heat up and transfer heat to the pan. This won't be nearly as efficient as a pan that is magnetic; so this is not recommended when possible to avoid. I'd try to return it for a new pan that does work.
That symbol means the manufacturer claims it is compatible; it's not a guarantee, of course, nobody is checking them, but it's a first start - and gives you more solid footing to do the return if it doesn't work.
Second, if you're shopping in person, bring a magnet with you. Note how well the magnet sticks to the pan. If it sticks immediately, then it's great; if it weakly sticks, then it might work - but may not be as efficient (I had a pan when I bought my cooktop that did have weak magnetism, but only worked about half the time - the sensor that determined the pan size didn't see the pan half the time; had to give that one away).
Third, make sure you're looking at the right kind of pan. Induction won't work well with a pan with a narrow base - like many woks - as the size of contact surface determines how well it heats. There are woks that can work with an induction stove, but it's very different from how they work on a gas stove. Wider bottom base is better for induction.
Finally, when you get the pan, see how quickly it heats up. Compare it to a pan you know works well. That will tell you if it's performing well - it should boil water quickly, for example.