Before diving too far into this, your image shows that you’re looking at your production catalog, rather than your sandbox catalog. Please be sure to launch your sandbox dashboard, as sandbox does not create catalog objects in your production dashboard. You can launch your sandbox dashboard from your apps page (https://developer.squareup.com/apps).
Also, I edited your initial post to remove the access token. I suggest you replace your access token in your dashboard as anyone that may have copied it before I redacted it now can make sandbox API calls on your account. Definitely a security risk to share your access tokens publicly, so please redact them in the future.