Backup in Subdomain

Hello, there is an issue with an actual webpage and I am thinking of recovering a backup of 2017, however we do not know if this backup includes all the content. So we thought we could publish it in an subdomain to check the backup.

I first thought that would be easy, I created the subdomain but then realized I could have problems with the database, etc, etc. …. How do I do this? I was going to migrate the backup with updraft to the subdomain.

Please, any help?

Thanks!