An Apple ID is the email address you use as a login for just about everything you do with Apple, including using iCloud to store your content, downloading PIM from the App Store, buying songs from the Apple Music, and downloading apps from the App Store
When setting up PIM for the first time it's worth sitting down and deciding how you will download PIM and which ID's will be used.
If you are going to be using an office device that will remain the possession of the business then we would recommend you setup an Apple ID linked to the business rather than a personal one. This then avoids issues where someone may leave employment and you wont have the password to update any Apps on the device including PIM.
If your employee uses their device, and then should they leave, all their inspections will be available in the PIM Cloud Dashboard for you to sync back down to another device. Just ensure that they have saved or submitted all their inspections.