unable to restore iphone 6s using catalina

I'm trying to restore an iPhone 6s that I haven't used in quite a while (hoping to gift it to my son). When I try to access the device, I get an error message, "iPhone is disabled connect to iTunes" (probably due to repeated unsuccessful attempts). So I went through all the steps listed on the apple care website re: restoring and/or updating the device. The problem is that - now that I have Catalina installed - I no longer have iTunes. And when I get to the very end of the steps, the computer asks, "Trust Eric's iPhone" (bold text); "To sync this computer with your iPhone, click Trust, then tap Trust on the device." Below this text there's the blue "Trust" button. However, I am unable to "tap Trust on the device" because the device is disabled.