"This account has reached its bucket limit"

Your provider returned TooManyBuckets, because this account can't hold another bucket. Delete a bucket you no longer use, or choose an existing bucket. Some providers can raise the limit if you ask them. Offloft only needs one bucket per site, and it can share a bucket by using a different path.

To use one bucket for two sites, set a different Path in bucket on each one, in Settings → Uploads & sync. That keeps their files apart.