How to automate a Lookup field using deluge?

How to automate a Lookup field using deluge?

I have a Multi-Select Lookup field that I need to auto-populate when a 'NETO' text field is populated.

Or, maybe make the Lookup field look up for the records based on the 'NETO' text field.

I tried creating a script to copy the 'NETO' text field to the Lookup field, but it does not work.

dealInfo = zoho.crm.getRecordById("Deals",dealId);
netoSOnum = ifnull(dealInfo.get("NETO"),"");
mp = Map();
mp.put("Lookup_field",netoSOnum);
upd = zoho.crm.updateRecord("Deals",dealId,mp,{"trigger":{"workflow"}});
info upd;

Need help please. Thank you!