Mac devices currently do not support multiple touch points for most touch screens. You will only get up to one point of touch without a third party driver in place.
Avocor has partnered with TouchBase to provide a multi-touch driver that is fully compatible and vetted with all Avocor touchscreens that are available on the market.
Free Trial Download:
NOTE: License fee may be required past the trial expiration date. For more information on purchasing your TouchBase license, please visit https://touch-base.com/