Family Dollar complaint: ADA violation from store manager

I am a US citizen with a medical condition that does not allow me to wear a facial covering. I am medically exempt from wearing a mask in public. As per NJ Governor Murphy’s executive order 122, persons with a medical exemption do not have to wear a mask in stores.
I attempted to purchase some items from the Woodbine, New Jersey location on May 13 at approximately 4:00pm, and the store manager refused to ring me up because I was not wearing a mask. I told her I could not wear a mask due to a medical condition and am medically exempt to wear one. She said she would not wait on me unless I wore a mask. I explained to her again that I am told by my doctor I cannot wear a mask and that her not serving me is in fact an ADA violation. She told me I had to leave the store. I asked if she would wait on me outside and she sarcastically said she couldn’t do that because she’s working. I told her I have a disability that will not allow me to put on a mask and she told me she wasn’t losing her job over it.
I would like someone to address this issue right away. This is not ok and your employees should be educated on this matter.