Without a loop:
Card_ID = [allData.CartridgeID]
With a loop, you will need a "for" statement such as
for i = 1 : length(allData)
Notice the colon instead of comma, and notice the "for". The code you had assigns 1 to i, displays the result, calculates length(allData) and throws away the result of that calculation.
How did you manage to get a 24 digit integer? The maximum integer for uint64 is only 20 digits. Perhaps the value is not really a 24 digit integer, but is instead (e.g.) a string? If it is then you need to store it to multiple output locations:
for i = 1 : length(allData)
Cart_ID(i,:) = allData(i).CartridgeID;
end
