google refusing access, unable to sync

Help please!
I re-installed Rainlendar Pro on my computer (Win10 64bit) after not having used it for a while and now I am unable to sync with Google, although previously there had been no issues.
Google seems to refuse access persistently. I have tried Application specific password from Google but that didn’t work either.
Can anybody help?

You are using an old version of Rainlendar. You need to upgrade to the latest version.