I seem to have a new problem now. After a while downloads seem to just stop, seems to be typically at 99% complete. Have you encountered this issue before?
I found this reddit user with a similar issue also using a PFsense router but replicating their fix didn't fix it for me.
For step 6, do you mean 'Type in 'rm ${DATA_DIR}/SteamPrefill/Config/account.config' and press ENTER'
This is what I had to add for it to work, but it did not seem to resolve my login issue unfortunately.