Using Row Number in Airtable and UpdateRowNumber

Help please. I am new and jsut getting my head around this tool, but I have 2 pages, once where it writes a row to and Airbook table, and as part of that stores the row number as a variable. On the other page I want to update the information on this row, so I have used the UpdateRowNumber componant. However, the row number I keep getting is ‘Object Object’!
Part of the first page-
Part of the 2nd page -

If I hard code the numbber it works, so I am a little stuck.
Thank you.