Share Sheet / Invite non-Zoho Member to join

Hi Zoho - great product(s)!

I'm new to Zoho myself and I'm trying to organise some testers to collaborate on a project. I've set up my spreadsheet and now I want to share it with them, but Zoho is telling me I can't because their email addresses are not Zoho accounts.

How I'd hoped it woud work would that Zoho would detect that an take that opportunity to grow it's userbase Facebook style by sending them an email:

Mr X has created a spreadsheet in Zoho and invites you to collaborate. Please click the link below to create a Zoho account.

Is that a good idea, or am I missing something? I did a search to see if this question has already been asked, but didn't find anything relevant.

Regards,
Peter

EDIT: Ahh, always the way. Once I posted this, it came up with "Related Posts" where someone said that Zoho doesn't send links to non Zoho members. That seems odd, most websites are desperate to send themselves to everyone in your address book.

EDIT 2: Now found the "Groups" functionality under Zoho Mail and added them to that which it seemed happy about (inconsistency?) but I'm not sure if that means...yes apparently I can add a group to the "Share" option on the sheet, but I tried that and it said it had failed to share the file. Maybe it'll work once one or more of my invitees create accounts...?

Sorry, obviously I'm following a learning curve here.