Soulver saves all your sheets, folders, custom units & variables, currencies and preferred region in a special file called a "sheetbook". Your default sheetbook is stored inside Soulver's application support folder at
You can move the default sheetbook to another location in Soulver's General preferences. Soulver can only open one sheetbook file at a time, so if you open another sheetbook file, your previously open sheetbook will be closed.
On your first Mac, go to Soulver > Preferences > General, and choose "Move…" to move the sheetbook you have been using into a synced folder (like Dropbox or iCloud Drive).
On your second Mac, go to Soulver > Preferences > General, and choose "Use other…" , and select the sheetbook file in the synced folder.