Back when the SNAP-SCM-W2 module was available we used Opto 22 to automate all of the Water and Wastewater sites for a City. Because we already had Opto 22 controls at these sites we just added a chart or two to handle the doors. We finally got rid of all the readers (maintenance) and now use groov view with a user account for each staff member to open doors. Originally we used a demo Opto 22 offered: https://www.opto22.com/support/resources-tools/downloads/door-controller-zip
You may be able to modify that to use serial RFID readers like these: