Hello, my save files were synced to the GOG servers and I used to play the W10 version, now with the macOS release I thought the save were compatible. Is there any way I can continue to play that save file?

The save files are compatible, but I don't know whether Galaxy can/will automatically synchronise the files across platforms. If not, you'll have to copy the saves manually.

On both Mac and Windows, the location of the saves is Documents\Larian Studios\Divinity Original Sin 2 Definitive Edition\PlayerProfiles\PROFILENAME\Savegames\Story

It's work, my friends.
When i start the game on my MBP I get my savegame from my PC.
And it's sync :)

Take care.