Try uninstalling old Sage 2015 client first (then reboot just to make sure). Try to run workstation setup for Sage 2021 after old Sage 2015 clients have been uninstalled.

I seem to be ok now.  My bad...figured out that they had Sentinel1 loaded on the server during my installation.  I reinstalled the software, rebooted the server and now I have a workstation setup.  I should have made sure the antivirus software was off first. 

I have the same problem.  So did you need to reinstall sage on the SERVER (with sentinelOne off) before you could get the workstation install to work properly?  Or just turn off SentinelOne on the workstation?

I reinstalled the software just incase Sentinel1 blocked any files from loading.  I had another issue just the other day when installed Product Update 4 on a server with Sentinel1 turned on.  It blocked pvxsec32.dll during the installation and then striped all the permissions from the existing file.  Had to reboot the server to get the permissions back.