Not a problem. Just run the installer again in downgrade mode and install the maps. Or follow the manual installation in the tutorial in Guides and Info.
Tutorial: 2020 North America 2.20 Map Installation (Stand-Alone without Reformat) with Updated NAV_Voice 06/21/2021 - Ford / Guides & Info - CyanLabs Official Community
To redo the installation with Syn3 Updater:
Fill out the present configuration as North America, NAV Yes, Version 3.4.21194
Save the config.
Go to the to program tab, select NA, Version you want to upgrade to, like 3.4.21194, and NA 2.20 maps.
Select start.
The app will download everything and place it on the USB. This could take a little time with the maps.
You will notice that the app will say downgrade mode. This is correct. The app will downgrade the present installation to 3.3.19052, then run the reformat tool to install everything.
There will be several reboots of the system. Do not remove the USB until you see the GREEN screen telling you to do so.
This will all take about 1/2 hour once the usb is inserted in the vehicle.