Hi @crumm welcome to the /e/ community.
The install instructions which I guess you are reading mention Heimdall, which is really a Linux product. Windows users have the (possibly) more easy Odin3.
I would suggest you try this howto: [HOWTO] Install /e/ on a Samsung smartphone with Windows easily
I had to update the phone to Android 10
No problem, you will have seen this caution
Caution: Before following these instructions please ensure that the device is on the latest Android Stock firmware. This can be done by checking for any OTA updates available in the Updater. If available run them before installing /e/OS
The important thing is that you install /e/ in the same version, Q, (as linked in the install instructions already mentioned).
- /e/OS build : Q dev