MontereyOS Install Error: "The volume cannot be used because it is a backup disc".
This is a repeat of a previously posted topic. This is in an office seting for an iMac (Built-in Retina, Radeon Pro 575 4096 MB graphics, 3 similar iMacs in office) with a shared Time Capsule backup system, however for some reason the hard drive on the computer in question is now the backup disc and not the Time Capsule. So I cannot install MontereyOS.
Please refer to a layperson's step by step process to allow MontereyOS to be installed and that I don't lose any data on the computer, and also how to prevent this from happening again.
Thanks!
iMac 27″ 5K, macOS 10.13