Virginia uses the Smart Health app. If you are in Virginia, check out this link to get started: Virginia Department of Health Announces Launch of QR Codes to Verify COVID-19 Vaccination Status - QR codes are secure and private for users, easy for businesses - Newsroom
I found this using a simple Google search. If you aren't in VA, see if your state has Smart Health. Just Google something like "digital vaccine cards for state name". It worked for me and hopefully Aruba will honor the Smart Health app.
Info on Smart Health app: SMART Health Card launches in some US states (covidpasscertificate.com)
Hope this helps!