How to auto number items on a project board in order to provide a count of them on an overarching tracker board through a mirror column.

Hi, I have an over-arching tracker board which reports the ey facts about a large number of lined project boards. Each line on the tracker relates to a individual contract which is for a certain number of credits, therefore on each project board each item represents one credit and I would lie to be able to auto-number the items so that I can add a mirror column of this to my tracker board which then gives a count of how many items there are on the board and therefore how many credits have been used on that contract.

I have tried the auto-number column but you cannot then mirror this elsewhere. The auto-ID column does not then allow you to do a count in the mirror column and I am then stuck as to how to do this. I would prefer to do it without a fee paying app integration if possible as it seems like something I should be able to do within Monday.com functionaity but I can’t work out how.

All suggestions welcomed
Many thanks
Celia