In the game file, where you can find the exe. There is an other file "Renpy".
Open it, search for the "savetoken.py" open it with the simple text editor, and then with the file open, press Ctrl+F and search for:
vk = ecdsa.VerifyingKey.from_der(key)
if vk.verify(sig, data):
return True
except Exception:
continue
return False
change the last entry to "True" save , restart the game and then your edited save will work.
As for editing, it can be done online through a save game editor like saveeditonline.