External Hard Drive

I have a 5 TB Seagate external hard drive connected to my M1 24 inch iMac running Ventura 13.2.1. It was set up as a Time Machine backup disc on my previous iMac. When I did the migration to my new iMac, the M1, it still showed up as a Time Machine disc, but was read-only so it was no use as a Time Machine. I have tried to make it read and write, but it won't let me change permissions. I have looked at all kinds of help articles but nothing has helped me. I tried running disc repair but that didn't work because of the read only. I unmounted the drive to try to remount it as a new disc, but now it won't remount (it doesn't show on my desktop). It does show in the System Report as being plugged in, but it is not mounted. How do I get the disc mounted and set up as a backup disc preferably as a Time Machine?