Update: after having to the other Android phone again, I was able to pair the two phones and transfer files. However, the new share dialog wouldn’t show up in the reglar app - i had to go into the webapp to see and accept the new share for the files to be transfered.
It was also quite painful to find the right location to put files: the help would say files are in /storage/emulated/0 if I input ~ but i had trouble finding that key - it would have been better to put files relative to ~ by default… If not directly in ~/Downloads.
It’s also not quite clear that it is better to create a new directory when accepting a share, maybe that should be the default behavior!