I too am getting the Javascript disabled error.
-Two step verification is turned off.
- I removed eM Client from approved apps.
- Non-trusted apps is turned off.
- I have tried manually adding as an other account (it just times out)
- I have tried adding with the automatic thingy and get:
Is there a fix for this yet? Last update I can find in a search is two years old and proposed solutions didn’t work. 