The trouble with the easy installer is, that it only offers the latest stable release, which is android 8 Oreo for the Samsung S9. As I mentioned before, if you were on a newer stock version, installation may not work:
If you don’t want to wait for the easy installer to support android 10 Q, your best bet I think would be to try manual installation. You’ve already got adb, Heimdall and TWRP installed through the easy installer, so starting from “Resize Userdata” should do the trick:
https://doc.e.foundation/devices/starlte/install
If you try this, you’ll probably need a newer patch though. The install doc links to version 1.0, but I’d try 6.1 mentioned in the thread I posted in my first reply (post no.21). (Sorry, the forum doesn’t allow me to post more than 2 links at a time.)