[Grammar] can use we them to refer to things?

[Ferdie11]

Hi,
Can you please tell me if I should use those instead of them in the sentence below. And can we use them to refer to things?

Please ask the user to check its files because some of them were not transferred successfully due to their filenames were too long.

Thanks in advance.

 

[5jj]

Please ask the user to check [STRIKE]its[/STRIKE] their files; (because) some of them were not transferred successfully, [STRIKE]due to[/STRIKE] as their file names were too long.

We can use them to refer to things.