The License File A:\PCAWIN.LIC is for version x.yy of PC Access. You must own version 4.00 to install this Upgrade edition of PC Access.
The license file the UAM found on the Disk 1 you inserted appears to be from a different version of PC Access than the UAM requires. You may only use the Upgrade edition of 4.20 with a PC Access 4.00 product. If you are sure you have a Disk 1 from a copy of PC Access version 4.00, follow the instructions for an Internal Error.