Problems with Migrating attachments from Salesforce to Zoho CRM

Problems with Migrating attachments from Salesforce to Zoho CRM

wizard works ok but cant create new custom fields for attachment module - we have quite a few text fields, user lookups that we would want linked.

can proceed without linking these but then the files are ALL skipped in the migration
csv for data and attachments folder with actual files

any advice appreciated we are evaluating zoho one but if we cant achieve this we may need to look elsewhere
cheers Michelle