Cannot log in to RealVNC server on Mac

Everything ran well for years using RealVNC to connect into my elderly mom's Macbook from my PC.  Had some issues with Safari on her mac that could only be corrected with an OS update.  Of course, this changed things for her in ways that were difficult but fixed the problem with being able to see all fields in the web version of Outlook.

One of the things that changed that is an actual problem is being able to connect to her computer to help her remotely.  I just get a black screen and couldn't fix it remotely.  I'm here now with her and the Macbook but can't get things to go - tried to update/reinstall RealVNC server and the installer simply won't allow me to log in.  I know I have the correct password as I can log in online to my account on the RealVNC website no problem.  I'd just wipe everything but even the uninstall function forces you to log into the RealVNC app, so I'm stuck.

I guess one weirdness is that the app/installer will populate the top box at login (assuming this is the user name) with her name and not the email address used to login to VNC's web page.  I can't log in either with this prepopulated name in that top (assume it's the username box, but it's not labelled) or the email address I use as the username on the VNC web page login.

Anyone have any idea?