I have a file saved with teams. The issue is using the file on lets say Facebook. When I choose to upload a file I can't point it at teams. I understand I can sync the library but is there a better way?
Actually Option 1 for sharing a link won't work in that use case, the people have to have Teams and access to that Team in that scenario.
Basically what you want to do and it's best case honestly, is to go to the channel the file is in. Click files tab, Click the "Open in SharePoint" link. then select the file you want to share and then click Share. Use the anyone with this Link option, and then Copy Link.
You can then take that link and paste it into Facebook, that way anytime they use that link they get the latest version of the document, and if you allowed editing they can edit the document and your copy gets updated in Teams instead of creating another document and breaking that document chain.
Groups usually by default however do not allow the "Anyone" link by default. You can change this now in the new SharePoint admin center under site management If you go to the group site, then on the info tab at the bottom you can update the sharing status to anyone. There is also a powershell command as well if you want it I'll dig it up, but the UI is easiest.