This is an indicator of macOS not having cleaned up a previous mount point. This is usually solved by rebooting, but can also easily be fixed manually:
Mount point /Volumes/Drive - [team name] already exists.Please unmount or remove it.
Go to /Volumes
There's an empty Drive - folder, delete it (password required)
Go back to Postlab, and connect Drive
Note: if this issue returns on the same computer, there's most likely a permissions issue. Get in touch.
Drive by itself doesn't need speed as there's little to no overhead, but your media's data rate can of course outpace your connection's download speed making live playback from the cloud impractical. The best way to handle that is a proxy workflow, to minimize the data rate of your media. If that is not possible, simply drag files from Drive to your hard drive - that will trigger a full file download, which you can do overnight.