Quick print error initializing

Hi! I am trying to use the quick print feature for my blog with 500+ entries, and I get an error that says “there seems to be an error initializing. Please verify you are using an up-to-date web browser. also check the WP REST API isn’t disabled by a security plugin. Feel free to contact Print My Blog support”. I am not a software engineer or expert in browsers, but I do have an up-to-date web browser. How can I check that the WP REST API isn’t disabled? I really appreciate it – really excited about this plug-in!