A:Answer Hello _,
Any external drive can backup as many computers as there is space on the external drive, through any number of ways.
The ability to backup multiple PCs using a bundled software depends mostly on the software licensing for the backup software and the operating systems of the PCs. Also, keep in mind that significant capacity may be needed to store all the files from the various computers, so be sure to purchase a drive large enough to handle your needs.
For information on how to store data on hard drives without the use of special software, check following link:
https://www.seagate.com/support/kb/how-to-use-an-external-drive-without-any-special-software-206419en/
Regards,
Zac
Seagate Support