Better to use syncthing, simple equivalent & free / open source.
I share files, what, once a year? Syncthing works great for that use case. If I want to share files too big to email, I can stand to upload to Onedrive/Dropbox/an open directory on my web server for that one-time use. For more frequent setups, sure an Owncloud/Nextcloud instance wouldn't be amiss.
I believe you when you say you've had problems performing file shares to arbitrary people, my comments were directed only that my use case is somewhat different.
Cheers!