If the SIM card is already activated and you were using it on another phone then it could be a couple things things besides it showing not compatible, non compatible phones will work but maybe limited to what they can do or may have issues. It could be to old to work on Visible, meaning the firmware of the phone isn't current enough to use Visible service, could be wrong though.
Are you sure the phone is actually unlocked? I had to do a Google search to find out how to check this on a phone and found the following on Pixel community:
You will need to enable developer options. Go to Settings > About phone > tap on 'Build number' until you see message that you're a developer.
After that go to Settings > System > Developer options > OEM unlocking - You do not want to toggle this on, as it's better security to have the bootloader locked. What you want to do is check whether you're able to toggle this setting on (and thus, unlocking the bootloader). If you can toggle it on, that means you have an unlocked phone. If not, that means your phone is locked to a carrier.
You may want to look for a more current phone, preferably one that is at least from 2022 and newer. Motorola has some current budget friendly phones. I had a G Power, 2022 model, and it was a good phone but I won't buy Motorola again because I prefer a phone that gets security updates for more than 2 years and switched to Samsung. Also, when Visible upgraded he system in 2022 they removed a lot of phones from the compatibility checker made prior to 2022. Some will still work but some may have issues with wi-fi calling, hotspot, visual voicemail, but had not heard reports of not connecting to service though.
